diff --git a/Isosurfacing_3/benchmark/Isosurfacing_3/benchmark.cpp b/Isosurfacing_3/benchmark/Isosurfacing_3/benchmark.cpp
index d71fb425fe2..b31ff45ad51 100644
--- a/Isosurfacing_3/benchmark/Isosurfacing_3/benchmark.cpp
+++ b/Isosurfacing_3/benchmark/Isosurfacing_3/benchmark.cpp
@@ -1,15 +1,18 @@
 #include <CGAL/Cartesian.h>
-#include <CGAL/Cartesian_grid_3.h>
-#include <CGAL/Explicit_cartesian_grid_gradient.h>
-#include <CGAL/Dual_contouring_3.h>
 #include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
-#include <CGAL/Explicit_cartesian_grid_domain.h>
-#include <CGAL/Implicit_cartesian_grid_domain.h>
-#include <CGAL/Marching_cubes_3.h>
-#include <CGAL/Polygon_mesh_processing/polygon_soup_to_polygon_mesh.h>
 #include <CGAL/Simple_cartesian.h>
 #include <CGAL/Surface_mesh.h>
+
+#include <CGAL/Isosurfacing_3/Cartesian_grid_3.h>
+#include <CGAL/Isosurfacing_3/Explicit_cartesian_grid_gradient.h>
+#include <CGAL/Isosurfacing_3/Dual_contouring_3.h>
+#include <CGAL/Isosurfacing_3/Explicit_cartesian_grid_domain.h>
+#include <CGAL/Isosurfacing_3/Implicit_cartesian_grid_domain.h>
+#include <CGAL/Isosurfacing_3/Marching_cubes_3.h>
+
+#include <CGAL/Polygon_mesh_processing/polygon_soup_to_polygon_mesh.h>
 #include <CGAL/boost/graph/IO/OFF.h>
+
 #include <math.h>
 
 #include <iostream>
diff --git a/Isosurfacing_3/examples/Isosurfacing_3/all_cartesian_cube.cpp b/Isosurfacing_3/examples/Isosurfacing_3/all_cartesian_cube.cpp
index 46c12a9b24e..24634884dfe 100644
--- a/Isosurfacing_3/examples/Isosurfacing_3/all_cartesian_cube.cpp
+++ b/Isosurfacing_3/examples/Isosurfacing_3/all_cartesian_cube.cpp
@@ -1,9 +1,9 @@
 #include <CGAL/Simple_cartesian.h>
 
-#include <CGAL/Cartesian_grid_3.h>
-#include <CGAL/Dual_contouring_3.h>
-#include <CGAL/Explicit_cartesian_grid_domain.h>
-#include <CGAL/Marching_cubes_3.h>
+#include <CGAL/Isosurfacing_3/Cartesian_grid_3.h>
+#include <CGAL/Isosurfacing_3/Dual_contouring_3.h>
+#include <CGAL/Isosurfacing_3/Explicit_cartesian_grid_domain.h>
+#include <CGAL/Isosurfacing_3/Marching_cubes_3.h>
 
 #include <CGAL/boost/graph/IO/OFF.h>
 
diff --git a/Isosurfacing_3/examples/Isosurfacing_3/dual_contouring_cartesian_grid.cpp b/Isosurfacing_3/examples/Isosurfacing_3/dual_contouring_cartesian_grid.cpp
index 3a83249456e..399f172ed3e 100644
--- a/Isosurfacing_3/examples/Isosurfacing_3/dual_contouring_cartesian_grid.cpp
+++ b/Isosurfacing_3/examples/Isosurfacing_3/dual_contouring_cartesian_grid.cpp
@@ -1,9 +1,9 @@
 #include <CGAL/Simple_cartesian.h>
 
-#include <CGAL/Cartesian_grid_3.h>
-#include <CGAL/Explicit_cartesian_grid_gradient.h>
-#include <CGAL/Dual_contouring_3.h>
-#include <CGAL/Explicit_cartesian_grid_domain.h>
+#include <CGAL/Isosurfacing_3/Cartesian_grid_3.h>
+#include <CGAL/Isosurfacing_3/Explicit_cartesian_grid_gradient.h>
+#include <CGAL/Isosurfacing_3/Explicit_cartesian_grid_domain.h>
+#include <CGAL/Isosurfacing_3/Dual_contouring_3.h>
 
 #include <CGAL/boost/graph/IO/OFF.h>
 
diff --git a/Isosurfacing_3/examples/Isosurfacing_3/dual_contouring_implicit_iwp.cpp b/Isosurfacing_3/examples/Isosurfacing_3/dual_contouring_implicit_iwp.cpp
index e5c5821064b..6888a06f3a9 100644
--- a/Isosurfacing_3/examples/Isosurfacing_3/dual_contouring_implicit_iwp.cpp
+++ b/Isosurfacing_3/examples/Isosurfacing_3/dual_contouring_implicit_iwp.cpp
@@ -1,9 +1,9 @@
 #include <CGAL/Simple_cartesian.h>
 
-#include <CGAL/Bbox_3.h>
-#include <CGAL/Dual_contouring_3.h>
-#include <CGAL/Implicit_cartesian_grid_domain.h>
+#include <CGAL/Isosurfacing_3/Dual_contouring_3.h>
+#include <CGAL/Isosurfacing_3/Implicit_cartesian_grid_domain.h>
 
+#include <CGAL/Bbox_3.h>
 #include <CGAL/boost/graph/IO/OFF.h>
 
 using Kernel = CGAL::Simple_cartesian<double>;
diff --git a/Isosurfacing_3/examples/Isosurfacing_3/dual_contouring_mesh_offset.cpp b/Isosurfacing_3/examples/Isosurfacing_3/dual_contouring_mesh_offset.cpp
index 8cd2715479f..62152acf13b 100644
--- a/Isosurfacing_3/examples/Isosurfacing_3/dual_contouring_mesh_offset.cpp
+++ b/Isosurfacing_3/examples/Isosurfacing_3/dual_contouring_mesh_offset.cpp
@@ -1,8 +1,8 @@
 #include <CGAL/Simple_cartesian.h>
 #include <CGAL/Surface_mesh.h>
 
-#include <CGAL/Dual_contouring_3.h>
-#include <CGAL/Implicit_cartesian_grid_domain.h>
+#include <CGAL/Isosurfacing_3/Dual_contouring_3.h>
+#include <CGAL/Isosurfacing_3/Implicit_cartesian_grid_domain.h>
 
 #include <CGAL/AABB_face_graph_triangle_primitive.h>
 #include <CGAL/AABB_traits.h>
@@ -13,6 +13,8 @@
 #include <CGAL/boost/graph/IO/OFF.h>
 
 #include <iostream>
+#include <string>
+#include <vector>
 
 using Kernel = CGAL::Simple_cartesian<double>;
 using FT = typename Kernel::FT;
diff --git a/Isosurfacing_3/examples/Isosurfacing_3/dual_contouring_octree.cpp b/Isosurfacing_3/examples/Isosurfacing_3/dual_contouring_octree.cpp
index 858e558377d..9fe5e1337bf 100644
--- a/Isosurfacing_3/examples/Isosurfacing_3/dual_contouring_octree.cpp
+++ b/Isosurfacing_3/examples/Isosurfacing_3/dual_contouring_octree.cpp
@@ -1,13 +1,15 @@
 #include <CGAL/Simple_cartesian.h>
 
-#include <CGAL/Dual_contouring_3.h>
-#include <CGAL/Implicit_octree_domain.h>
-#include <CGAL/Octree_wrapper.h>
+#include <CGAL/Isosurfacing_3/Dual_contouring_3.h>
+#include <CGAL/Isosurfacing_3/Implicit_octree_domain.h>
+#include <CGAL/Isosurfacing_3/internal/Octree_wrapper.h>
 
 #include <CGAL/boost/graph/IO/OFF.h>
 
 #include <iostream>
 #include <math.h>
+#include <memory>
+#include <vector>
 
 using Kernel = CGAL::Simple_cartesian<double>;
 using FT = typename Kernel::FT;
@@ -17,7 +19,7 @@ using Point = typename Kernel::Point_3;
 using Point_range = std::vector<Point>;
 using Polygon_range = std::vector<std::vector<std::size_t> >;
 
-using Octree_wrapper_ = CGAL::Isosurfacing::Octree_wrapper<Kernel>;
+using Octree_wrapper_ = CGAL::Isosurfacing::internal::Octree_wrapper<Kernel>;
 
 struct Refine_one_eighth
 {
diff --git a/Isosurfacing_3/examples/Isosurfacing_3/marching_cubes_cartesian_grid_sphere.cpp b/Isosurfacing_3/examples/Isosurfacing_3/marching_cubes_cartesian_grid_sphere.cpp
index 280a1508023..0107b2890c2 100644
--- a/Isosurfacing_3/examples/Isosurfacing_3/marching_cubes_cartesian_grid_sphere.cpp
+++ b/Isosurfacing_3/examples/Isosurfacing_3/marching_cubes_cartesian_grid_sphere.cpp
@@ -1,10 +1,15 @@
 
-#include <CGAL/Cartesian_grid_3.h>
-#include <CGAL/Explicit_cartesian_grid_domain.h>
-#include <CGAL/Marching_cubes_3.h>
 #include <CGAL/Simple_cartesian.h>
+
+#include <CGAL/Isosurfacing_3/Cartesian_grid_3.h>
+#include <CGAL/Isosurfacing_3/Explicit_cartesian_grid_domain.h>
+#include <CGAL/Isosurfacing_3/Marching_cubes_3.h>
+
 #include <CGAL/boost/graph/IO/OFF.h>
 
+#include <memory>
+#include <vector>
+
 using Kernel = CGAL::Simple_cartesian<double>;
 using FT = typename Kernel::FT;
 using Point = typename Kernel::Point_3;
diff --git a/Isosurfacing_3/examples/Isosurfacing_3/marching_cubes_implicit_sphere.cpp b/Isosurfacing_3/examples/Isosurfacing_3/marching_cubes_implicit_sphere.cpp
index e90acf5a9fd..ed7fbe505cb 100644
--- a/Isosurfacing_3/examples/Isosurfacing_3/marching_cubes_implicit_sphere.cpp
+++ b/Isosurfacing_3/examples/Isosurfacing_3/marching_cubes_implicit_sphere.cpp
@@ -1,11 +1,14 @@
 #include <CGAL/Simple_cartesian.h>
 
+#include <CGAL/Isosurfacing_3/Implicit_cartesian_grid_domain.h>
+#include <CGAL/Isosurfacing_3/Marching_cubes_3.h>
+
 #include <CGAL/Bbox_3.h>
-#include <CGAL/Implicit_cartesian_grid_domain.h>
-#include <CGAL/Marching_cubes_3.h>
 
 #include <CGAL/boost/graph/IO/OFF.h>
 
+#include <vector>
+
 using Kernel = CGAL::Simple_cartesian<double>;
 using FT = typename Kernel::FT;
 using Vector = typename Kernel::Vector_3;
diff --git a/Isosurfacing_3/examples/Isosurfacing_3/marching_cubes_inrimage.cpp b/Isosurfacing_3/examples/Isosurfacing_3/marching_cubes_inrimage.cpp
index dee94271ff1..f88fe980659 100644
--- a/Isosurfacing_3/examples/Isosurfacing_3/marching_cubes_inrimage.cpp
+++ b/Isosurfacing_3/examples/Isosurfacing_3/marching_cubes_inrimage.cpp
@@ -1,11 +1,14 @@
 #include <CGAL/Simple_cartesian.h>
 
-#include <CGAL/Cartesian_grid_3.h>
-#include <CGAL/Explicit_cartesian_grid_domain.h>
-#include <CGAL/Marching_cubes_3.h>
+#include <CGAL/Isosurfacing_3/Cartesian_grid_3.h>
+#include <CGAL/Isosurfacing_3/Explicit_cartesian_grid_domain.h>
+#include <CGAL/Isosurfacing_3/Marching_cubes_3.h>
 
 #include <CGAL/boost/graph/IO/OFF.h>
 
+#include <memory>
+#include <vector>
+
 using Kernel = CGAL::Simple_cartesian<double>;
 using Point = typename Kernel::Point_3;
 using Grid = CGAL::Cartesian_grid_3<Kernel>;
diff --git a/Isosurfacing_3/examples/Isosurfacing_3/marching_cubes_signed_mesh_offset.cpp b/Isosurfacing_3/examples/Isosurfacing_3/marching_cubes_signed_mesh_offset.cpp
index ad63f02e17e..31b7a8615ed 100644
--- a/Isosurfacing_3/examples/Isosurfacing_3/marching_cubes_signed_mesh_offset.cpp
+++ b/Isosurfacing_3/examples/Isosurfacing_3/marching_cubes_signed_mesh_offset.cpp
@@ -1,17 +1,20 @@
 #include <CGAL/Simple_cartesian.h>
 #include <CGAL/Surface_mesh.h>
 
+#include <CGAL/Isosurfacing_3/Cartesian_grid_3.h>
+#include <CGAL/Isosurfacing_3/Explicit_cartesian_grid_domain.h>
+#include <CGAL/Isosurfacing_3/Marching_cubes_3.h>
+
 #include <CGAL/AABB_face_graph_triangle_primitive.h>
 #include <CGAL/AABB_traits.h>
 #include <CGAL/AABB_tree.h>
-#include <CGAL/Cartesian_grid_3.h>
-#include <CGAL/Explicit_cartesian_grid_domain.h>
-#include <CGAL/Marching_cubes_3.h>
 #include <CGAL/Side_of_triangle_mesh.h>
 
 #include <CGAL/boost/graph/IO/OFF.h>
 
 #include <iostream>
+#include <memory>
+#include <vector>
 
 using Kernel = CGAL::Simple_cartesian<double>;
 using FT = typename Kernel::FT;
diff --git a/Isosurfacing_3/include/CGAL/Cartesian_grid_3.h b/Isosurfacing_3/include/CGAL/Isosurfacing_3/Cartesian_grid_3.h
similarity index 98%
rename from Isosurfacing_3/include/CGAL/Cartesian_grid_3.h
rename to Isosurfacing_3/include/CGAL/Isosurfacing_3/Cartesian_grid_3.h
index 0df6f02a714..06b3ef56a6d 100644
--- a/Isosurfacing_3/include/CGAL/Cartesian_grid_3.h
+++ b/Isosurfacing_3/include/CGAL/Isosurfacing_3/Cartesian_grid_3.h
@@ -9,8 +9,8 @@
 //
 // Author(s)     : Julian Stahl
 
-#ifndef CGAL_CARTESIAN_GRID_3_H
-#define CGAL_CARTESIAN_GRID_3_H
+#ifndef CGAL_ISOSURFACING_3_CARTESIAN_GRID_3_H
+#define CGAL_ISOSURFACING_3_CARTESIAN_GRID_3_H
 
 #include <CGAL/license/Isosurfacing_3.h>
 
@@ -295,4 +295,4 @@ to_image() const
 
 } // namespace CGAL
 
-#endif // CGAL_CARTESIAN_GRID_3_H
+#endif // CGAL_ISOSURFACING_3_CARTESIAN_GRID_3_H
diff --git a/Isosurfacing_3/include/CGAL/Dual_contouring_3.h b/Isosurfacing_3/include/CGAL/Isosurfacing_3/Dual_contouring_3.h
similarity index 95%
rename from Isosurfacing_3/include/CGAL/Dual_contouring_3.h
rename to Isosurfacing_3/include/CGAL/Isosurfacing_3/Dual_contouring_3.h
index 7623d147d06..77ac3442e73 100644
--- a/Isosurfacing_3/include/CGAL/Dual_contouring_3.h
+++ b/Isosurfacing_3/include/CGAL/Isosurfacing_3/Dual_contouring_3.h
@@ -10,12 +10,13 @@
 // Author(s)     : Julian Stahl
 //                 Daniel Zint
 
-#ifndef CGAL_DUAL_CONTOURING_3_H
-#define CGAL_DUAL_CONTOURING_3_H
+#ifndef CGAL_ISOSURFACING_3_DUAL_CONTOURING_3_H
+#define CGAL_ISOSURFACING_3_DUAL_CONTOURING_3_H
 
 #include <CGAL/license/Isosurfacing_3.h>
 
 #include <CGAL/Isosurfacing_3/internal/Dual_contouring_internal.h>
+
 #include <CGAL/tags.h>
 
 namespace CGAL {
@@ -93,4 +94,4 @@ void dual_contouring(const Domain_& domain,
 } // namespace Isosurfacing
 } // namespace CGAL
 
-#endif // CGAL_DUAL_CONTOURING_3_H
+#endif // CGAL_ISOSURFACING_3_DUAL_CONTOURING_3_H
diff --git a/Isosurfacing_3/include/CGAL/Explicit_cartesian_grid_domain.h b/Isosurfacing_3/include/CGAL/Isosurfacing_3/Explicit_cartesian_grid_domain.h
similarity index 91%
rename from Isosurfacing_3/include/CGAL/Explicit_cartesian_grid_domain.h
rename to Isosurfacing_3/include/CGAL/Isosurfacing_3/Explicit_cartesian_grid_domain.h
index 651da15c40a..23e8750bf94 100644
--- a/Isosurfacing_3/include/CGAL/Explicit_cartesian_grid_domain.h
+++ b/Isosurfacing_3/include/CGAL/Isosurfacing_3/Explicit_cartesian_grid_domain.h
@@ -9,16 +9,17 @@
 //
 // Author(s)     : Julian Stahl
 
-#ifndef CGAL_EXPLICIT_CARTESIAN_GRID_DOMAIN_H
-#define CGAL_EXPLICIT_CARTESIAN_GRID_DOMAIN_H
+#ifndef CGAL_ISOSURFACING_3_EXPLICIT_CARTESIAN_GRID_DOMAIN_H
+#define CGAL_ISOSURFACING_3_EXPLICIT_CARTESIAN_GRID_DOMAIN_H
 
 #include <CGAL/license/Isosurfacing_3.h>
 
-#include <CGAL/Cartesian_grid_3.h>
 #include <CGAL/Isosurfacing_3/internal/Base_domain.h>
 #include <CGAL/Isosurfacing_3/internal/Cartesian_grid_geometry.h>
 #include <CGAL/Isosurfacing_3/internal/Grid_topology.h>
-#include <CGAL/Zero_gradient.h>
+
+#include <CGAL/Isosurfacing_3/Cartesian_grid_3.h>
+#include <CGAL/Isosurfacing_3/Zero_gradient.h>
 
 namespace CGAL {
 namespace Isosurfacing {
@@ -89,4 +90,4 @@ create_explicit_cartesian_grid_domain(const std::shared_ptr<Cartesian_grid_3<Geo
 } // namespace Isosurfacing
 } // namespace CGAL
 
-#endif // CGAL_EXPLICIT_CARTESIAN_GRID_DOMAIN_H
+#endif // CGAL_ISOSURFACING_3_EXPLICIT_CARTESIAN_GRID_DOMAIN_H
diff --git a/Isosurfacing_3/include/CGAL/Explicit_cartesian_grid_gradient.h b/Isosurfacing_3/include/CGAL/Isosurfacing_3/Explicit_cartesian_grid_gradient.h
similarity index 93%
rename from Isosurfacing_3/include/CGAL/Explicit_cartesian_grid_gradient.h
rename to Isosurfacing_3/include/CGAL/Isosurfacing_3/Explicit_cartesian_grid_gradient.h
index 7a9d666be77..74129037f12 100644
--- a/Isosurfacing_3/include/CGAL/Explicit_cartesian_grid_gradient.h
+++ b/Isosurfacing_3/include/CGAL/Isosurfacing_3/Explicit_cartesian_grid_gradient.h
@@ -9,13 +9,16 @@
 //
 // Author(s)     : Julian Stahl
 
-#ifndef CGAL_EXPLICIT_CARTESIAN_GRID_GRADIENT_H
-#define CGAL_EXPLICIT_CARTESIAN_GRID_GRADIENT_H
+#ifndef CGAL_ISOSURFACING_3_EXPLICIT_CARTESIAN_GRID_GRADIENT_H
+#define CGAL_ISOSURFACING_3_EXPLICIT_CARTESIAN_GRID_GRADIENT_H
 
 #include <CGAL/license/Isosurfacing_3.h>
 
+#include <CGAL/Isosurfacing_3/Cartesian_grid_3.h>
+
 #include <CGAL/Bbox_3.h>
-#include <CGAL/Cartesian_grid_3.h>
+
+#include <memory>
 
 namespace CGAL {
 namespace Isosurfacing {
@@ -121,4 +124,4 @@ private:
 } // namespace Isosurfacing
 } // namespace CGAL
 
-#endif // CGAL_EXPLICIT_CARTESIAN_GRID_GRADIENT_H
+#endif // CGAL_ISOSURFACING_3_EXPLICIT_CARTESIAN_GRID_GRADIENT_H
diff --git a/Isosurfacing_3/include/CGAL/Finite_difference_gradient.h b/Isosurfacing_3/include/CGAL/Isosurfacing_3/Finite_difference_gradient.h
similarity index 93%
rename from Isosurfacing_3/include/CGAL/Finite_difference_gradient.h
rename to Isosurfacing_3/include/CGAL/Isosurfacing_3/Finite_difference_gradient.h
index b125996724b..d3fe86640f5 100644
--- a/Isosurfacing_3/include/CGAL/Finite_difference_gradient.h
+++ b/Isosurfacing_3/include/CGAL/Isosurfacing_3/Finite_difference_gradient.h
@@ -9,8 +9,8 @@
 //
 // Author(s)     : Julian Stahl
 
-#ifndef CGAL_FINITE_DIFFERENCE_GRADIENT_H
-#define CGAL_FINITE_DIFFERENCE_GRADIENT_H
+#ifndef CGAL_ISOSURFACING_3_FINITE_DIFFERENCE_GRADIENT_H
+#define CGAL_ISOSURFACING_3_FINITE_DIFFERENCE_GRADIENT_H
 
 #include <CGAL/license/Isosurfacing_3.h>
 
@@ -88,4 +88,4 @@ private:
 } // namespace Isosurfacing
 } // namespace CGAL
 
-#endif // CGAL_FINITE_DIFFERENCE_GRADIENT_H
+#endif // CGAL_ISOSURFACING_3_FINITE_DIFFERENCE_GRADIENT_H
diff --git a/Isosurfacing_3/include/CGAL/Implicit_cartesian_grid_domain.h b/Isosurfacing_3/include/CGAL/Isosurfacing_3/Implicit_cartesian_grid_domain.h
similarity index 95%
rename from Isosurfacing_3/include/CGAL/Implicit_cartesian_grid_domain.h
rename to Isosurfacing_3/include/CGAL/Isosurfacing_3/Implicit_cartesian_grid_domain.h
index b856c67d86e..6c3b2c61109 100644
--- a/Isosurfacing_3/include/CGAL/Implicit_cartesian_grid_domain.h
+++ b/Isosurfacing_3/include/CGAL/Isosurfacing_3/Implicit_cartesian_grid_domain.h
@@ -9,8 +9,8 @@
 //
 // Author(s)     : Julian Stahl
 
-#ifndef CGAL_IMPLICIT_CARTESIAN_GRID_DOMAIN_H
-#define CGAL_IMPLICIT_CARTESIAN_GRID_DOMAIN_H
+#ifndef CGAL_ISOSURFACING_3_IMPLICIT_CARTESIAN_GRID_DOMAIN_H
+#define CGAL_ISOSURFACING_3_IMPLICIT_CARTESIAN_GRID_DOMAIN_H
 
 #include <CGAL/license/Isosurfacing_3.h>
 
@@ -18,7 +18,8 @@
 #include <CGAL/Isosurfacing_3/internal/Cartesian_grid_geometry.h>
 #include <CGAL/Isosurfacing_3/internal/Grid_topology.h>
 #include <CGAL/Isosurfacing_3/internal/Implicit_function_with_geometry.h>
-#include <CGAL/Zero_gradient.h>
+#include <CGAL/Isosurfacing_3/Zero_gradient.h>
+
 #include <CGAL/Bbox_3.h>
 
 namespace CGAL {
@@ -105,4 +106,4 @@ create_implicit_cartesian_grid_domain(const Bbox_3& bbox,
 } // namespace Isosurfacing
 } // namespace CGAL
 
-#endif // CGAL_IMPLICIT_CARTESIAN_GRID_DOMAIN_H
+#endif // CGAL_ISOSURFACING_3_IMPLICIT_CARTESIAN_GRID_DOMAIN_H
diff --git a/Isosurfacing_3/include/CGAL/Implicit_octree_domain.h b/Isosurfacing_3/include/CGAL/Isosurfacing_3/Implicit_octree_domain.h
similarity index 86%
rename from Isosurfacing_3/include/CGAL/Implicit_octree_domain.h
rename to Isosurfacing_3/include/CGAL/Isosurfacing_3/Implicit_octree_domain.h
index ecadd4e39cf..c74ce931cc5 100644
--- a/Isosurfacing_3/include/CGAL/Implicit_octree_domain.h
+++ b/Isosurfacing_3/include/CGAL/Isosurfacing_3/Implicit_octree_domain.h
@@ -9,8 +9,8 @@
 //
 // Author(s)     : Julian Stahl
 
-#ifndef CGAL_IMPLICIT_OCTREE_DOMAIN_H
-#define CGAL_IMPLICIT_OCTREE_DOMAIN_H
+#ifndef CGAL_ISOSURFACING_3_IMPLICIT_OCTREE_DOMAIN_H
+#define CGAL_ISOSURFACING_3_IMPLICIT_OCTREE_DOMAIN_H
 
 #include <CGAL/license/Isosurfacing_3.h>
 
@@ -18,8 +18,8 @@
 #include <CGAL/Isosurfacing_3/internal/Implicit_function_with_geometry.h>
 #include <CGAL/Isosurfacing_3/internal/Octree_geometry.h>
 #include <CGAL/Isosurfacing_3/internal/Octree_topology.h>
-#include <CGAL/Octree_wrapper.h>
-#include <CGAL/Zero_gradient.h>
+#include <CGAL/Isosurfacing_3/internal/Octree_wrapper.h>
+#include <CGAL/Isosurfacing_3/Zero_gradient.h>
 
 namespace CGAL {
 namespace Isosurfacing {
@@ -40,7 +40,7 @@ template <typename GeomTraits,
           typename PointFunction,
           typename Gradient_ = Zero_gradient<GeomTraits> >
 Implicit_octree_domain<GeomTraits, PointFunction, Gradient_>
-create_implicit_octree_domain(const std::shared_ptr<Octree_wrapper<GeomTraits> > octree,
+create_implicit_octree_domain(const std::shared_ptr<internal::Octree_wrapper<GeomTraits> > octree,
                               const PointFunction& point_function,
                               const Gradient_& gradient = Gradient_())
 {
@@ -66,4 +66,4 @@ create_implicit_octree_domain(const std::shared_ptr<Octree_wrapper<GeomTraits> >
 } // namespace Isosurfacing
 } // namespace CGAL
 
-#endif // CGAL_IMPLICIT_OCTREE_DOMAIN_H
+#endif // CGAL_ISOSURFACING_3_IMPLICIT_OCTREE_DOMAIN_H
diff --git a/Isosurfacing_3/include/CGAL/Marching_cubes_3.h b/Isosurfacing_3/include/CGAL/Isosurfacing_3/Marching_cubes_3.h
similarity index 94%
rename from Isosurfacing_3/include/CGAL/Marching_cubes_3.h
rename to Isosurfacing_3/include/CGAL/Isosurfacing_3/Marching_cubes_3.h
index efe548911d1..3680d4ae21c 100644
--- a/Isosurfacing_3/include/CGAL/Marching_cubes_3.h
+++ b/Isosurfacing_3/include/CGAL/Isosurfacing_3/Marching_cubes_3.h
@@ -9,8 +9,8 @@
 //
 // Author(s)     : Julian Stahl
 
-#ifndef CGAL_MARCHING_CUBES_3_H
-#define CGAL_MARCHING_CUBES_3_H
+#ifndef CGAL_ISOSURFACING_3_MARCHING_CUBES_3_H
+#define CGAL_ISOSURFACING_3_MARCHING_CUBES_3_H
 
 #include <CGAL/license/Isosurfacing_3.h>
 
@@ -74,4 +74,4 @@ void marching_cubes(const Domain_& domain,
 } // namespace Isosurfacing
 } // namespace CGAL
 
-#endif // CGAL_MARCHING_CUBES_3_H
+#endif // CGAL_ISOSURFACING_3_MARCHING_CUBES_3_H
diff --git a/Isosurfacing_3/include/CGAL/Zero_gradient.h b/Isosurfacing_3/include/CGAL/Isosurfacing_3/Zero_gradient.h
similarity index 89%
rename from Isosurfacing_3/include/CGAL/Zero_gradient.h
rename to Isosurfacing_3/include/CGAL/Isosurfacing_3/Zero_gradient.h
index ca24decd821..3d4a7d57c65 100644
--- a/Isosurfacing_3/include/CGAL/Zero_gradient.h
+++ b/Isosurfacing_3/include/CGAL/Isosurfacing_3/Zero_gradient.h
@@ -9,8 +9,8 @@
 //
 // Author(s)     : Julian Stahl
 
-#ifndef CGAL_ZERO_GRADIENT_H
-#define CGAL_ZERO_GRADIENT_H
+#ifndef CGAL_ISOSURFACING_3_ZERO_GRADIENT_H
+#define CGAL_ISOSURFACING_3_ZERO_GRADIENT_H
 
 #include <CGAL/license/Isosurfacing_3.h>
 
@@ -54,4 +54,4 @@ private:
 } // namespace Isosurfacing
 } // namespace CGAL
 
-#endif // CGAL_ZERO_GRADIENT_H
+#endif // CGAL_ISOSURFACING_3_ZERO_GRADIENT_H
diff --git a/Isosurfacing_3/include/CGAL/Isosurfacing_3/internal/Octree_geometry.h b/Isosurfacing_3/include/CGAL/Isosurfacing_3/internal/Octree_geometry.h
index a91b58ae495..17f7545803a 100644
--- a/Isosurfacing_3/include/CGAL/Isosurfacing_3/internal/Octree_geometry.h
+++ b/Isosurfacing_3/include/CGAL/Isosurfacing_3/internal/Octree_geometry.h
@@ -15,7 +15,7 @@
 #include <CGAL/license/Isosurfacing_3.h>
 
 #include <CGAL/Isosurfacing_3/internal/Octree_topology.h>
-#include <CGAL/Octree_wrapper.h>
+#include <CGAL/Isosurfacing_3/internal/Octree_wrapper.h>
 
 #include <memory>
 
diff --git a/Isosurfacing_3/include/CGAL/Isosurfacing_3/internal/Octree_topology.h b/Isosurfacing_3/include/CGAL/Isosurfacing_3/internal/Octree_topology.h
index 0621122d113..e02743b9c4b 100644
--- a/Isosurfacing_3/include/CGAL/Isosurfacing_3/internal/Octree_topology.h
+++ b/Isosurfacing_3/include/CGAL/Isosurfacing_3/internal/Octree_topology.h
@@ -15,7 +15,8 @@
 #include <CGAL/license/Isosurfacing_3.h>
 
 #include <CGAL/Isosurfacing_3/internal/Cell_type.h>
-#include <CGAL/Octree_wrapper.h>
+#include <CGAL/Isosurfacing_3/internal/Octree_wrapper.h>
+
 #include <CGAL/tags.h>
 
 #ifdef CGAL_LINKED_WITH_TBB
diff --git a/Isosurfacing_3/include/CGAL/Octree_wrapper.h b/Isosurfacing_3/include/CGAL/Isosurfacing_3/internal/Octree_wrapper.h
similarity index 98%
rename from Isosurfacing_3/include/CGAL/Octree_wrapper.h
rename to Isosurfacing_3/include/CGAL/Isosurfacing_3/internal/Octree_wrapper.h
index 0ae0191cf0c..22f75102a27 100644
--- a/Isosurfacing_3/include/CGAL/Octree_wrapper.h
+++ b/Isosurfacing_3/include/CGAL/Isosurfacing_3/internal/Octree_wrapper.h
@@ -10,8 +10,8 @@
 // Author(s)     : Daniel Zint
 //                 Julian Stahl
 
-#ifndef CGAL_OCTREE_WRAPPER_H
-#define CGAL_OCTREE_WRAPPER_H
+#ifndef CGAL_ISOSURFACING_3_INTERNAL_OCTREE_WRAPPER_H
+#define CGAL_ISOSURFACING_3_INTERNAL_OCTREE_WRAPPER_H
 
 #include <CGAL/license/Isosurfacing_3.h>
 
@@ -21,6 +21,7 @@
 
 namespace CGAL {
 namespace Isosurfacing {
+namespace internal {
 
 template <typename GeomTraits>
 class Octree_wrapper
@@ -605,7 +606,8 @@ public:
   }
 };
 
+} // namespace internal
 } // namespace Isosurfacing
 } // namespace CGAL
 
-#endif // CGAL_OCTREE_WRAPPER_H
+#endif // CGAL_ISOSURFACING_3_INTERNAL_OCTREE_WRAPPER_H
diff --git a/Isosurfacing_3/test/Isosurfacing_3/test_dual_contouring.cpp b/Isosurfacing_3/test/Isosurfacing_3/test_dual_contouring.cpp
index 50c6a4a31a9..226303ce1d7 100644
--- a/Isosurfacing_3/test/Isosurfacing_3/test_dual_contouring.cpp
+++ b/Isosurfacing_3/test/Isosurfacing_3/test_dual_contouring.cpp
@@ -1,16 +1,17 @@
 #include <CGAL/Simple_cartesian.h>
 #include <CGAL/Surface_mesh.h>
 
-#include <CGAL/Cartesian_grid_3.h>
-#include <CGAL/Dual_contouring_3.h>
-#include <CGAL/Explicit_cartesian_grid_domain.h>
-#include <CGAL/Implicit_cartesian_grid_domain.h>
-#include <CGAL/Marching_cubes_3.h>
-#include <CGAL/Octree_wrapper.h>
-#include <CGAL/Polygon_mesh_processing/polygon_soup_to_polygon_mesh.h>
+#include <CGAL/Isosurfacing_3/internal/Octree_wrapper.h>
 
+#include <CGAL/Isosurfacing_3/Cartesian_grid_3.h>
+#include <CGAL/Isosurfacing_3/Dual_contouring_3.h>
+#include <CGAL/Isosurfacing_3/Explicit_cartesian_grid_domain.h>
+#include <CGAL/Isosurfacing_3/Finite_difference_gradient.h>
+#include <CGAL/Isosurfacing_3/Implicit_cartesian_grid_domain.h>
+#include <CGAL/Isosurfacing_3/Marching_cubes_3.h>
+
+#include <CGAL/Polygon_mesh_processing/polygon_soup_to_polygon_mesh.h>
 #include <CGAL/boost/graph/IO/OFF.h>
-#include <CGAL/Finite_difference_gradient.h>
 
 #include "Timer.h"
 
@@ -19,7 +20,7 @@ using Vector = typename Kernel::Vector_3;
 using Point = typename Kernel::Point_3;
 
 using Mesh = CGAL::Surface_mesh<Point>;
-using Grid CGAL::Cartesian_grid_3<Kernel>;
+using Grid = CGAL::Cartesian_grid_3<Kernel>;
 
 using Point_range = std::vector<Point>;
 using Polygon_range = std::vector<std::vector<std::size_t> >;
diff --git a/Isosurfacing_3/test/Isosurfacing_3/test_marching_cubes.cpp b/Isosurfacing_3/test/Isosurfacing_3/test_marching_cubes.cpp
index e3067e6a0e8..74db4d4b32e 100644
--- a/Isosurfacing_3/test/Isosurfacing_3/test_marching_cubes.cpp
+++ b/Isosurfacing_3/test/Isosurfacing_3/test_marching_cubes.cpp
@@ -1,8 +1,11 @@
 
-#include <CGAL/Marching_cubes_3.h>
+#include <CGAL/Isosurfacing_3/Marching_cubes_3.h>
 
 #include "test_util.h"
 
+#include <iostream>
+#include <string>
+
 #define WRITE_OFF
 
 struct Sphere_function
diff --git a/Isosurfacing_3/test/Isosurfacing_3/test_util.h b/Isosurfacing_3/test/Isosurfacing_3/test_util.h
index 737c7e62a8d..28d783f9655 100644
--- a/Isosurfacing_3/test/Isosurfacing_3/test_util.h
+++ b/Isosurfacing_3/test/Isosurfacing_3/test_util.h
@@ -4,9 +4,10 @@
 #include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
 #include <CGAL/Surface_mesh.h>
 
-#include <CGAL/Cartesian_grid_3.h>
-#include <CGAL/Explicit_cartesian_grid_domain.h>
-#include <CGAL/Implicit_cartesian_grid_domain.h>
+#include <CGAL/Isosurfacing_3/Cartesian_grid_3.h>
+#include <CGAL/Isosurfacing_3/Explicit_cartesian_grid_domain.h>
+#include <CGAL/Isosurfacing_3/Implicit_cartesian_grid_domain.h>
+
 #include <CGAL/Polygon_mesh_processing/distance.h>
 #include <CGAL/Polygon_mesh_processing/manifoldness.h>
 #include <CGAL/Polygon_mesh_processing/polygon_soup_to_polygon_mesh.h>