diff --git a/Combinatorial_map/include/CGAL/Combinatorial_map.h b/Combinatorial_map/include/CGAL/Combinatorial_map.h
index d7ff7469919..4dd8e7822d8 100644
--- a/Combinatorial_map/include/CGAL/Combinatorial_map.h
+++ b/Combinatorial_map/include/CGAL/Combinatorial_map.h
@@ -44,7 +44,6 @@
 #include <tuple>
 #include <unordered_map>
 #include <boost/type_traits/is_same.hpp>
-#include <boost/unordered_map.hpp>
 #include <boost/graph/graph_traits.hpp>
 #include <CGAL/boost/graph/helpers.h>
 
@@ -231,8 +230,8 @@ namespace CGAL {
               typename Converters, typename DartInfoConverter,
               typename PointConverter>
     void generic_copy(CMap2& amap,
-                      boost::unordered_map<Dart_handle_2, Dart_handle>* origin_to_copy,
-                      boost::unordered_map<Dart_handle, Dart_handle_2>* copy_to_origin,
+                      std::unordered_map<Dart_handle_2, Dart_handle>* origin_to_copy,
+                      std::unordered_map<Dart_handle, Dart_handle_2>* copy_to_origin,
                       const Converters& converters,
                       const DartInfoConverter& dartinfoconverter,
                       const PointConverter& pointconverter,
@@ -260,7 +259,7 @@ namespace CGAL {
       // Create an mapping between darts of the two maps (originals->copies).
       // (here we cannot use CGAL::Unique_hash_map because it does not provide
       // iterators...
-      boost::unordered_map<Dart_handle_2, Dart_handle> local_dartmap;
+      std::unordered_map<Dart_handle_2, Dart_handle> local_dartmap;
       if (origin_to_copy==NULL) // Use local_dartmap if user does not provides its own unordered_map
       { origin_to_copy=&local_dartmap; }
 
@@ -288,7 +287,7 @@ namespace CGAL {
 
       unsigned int min_dim=(dimension<amap.dimension?dimension:amap.dimension);
 
-      typename boost::unordered_map<Dart_handle_2,Dart_handle>::iterator
+      typename std::unordered_map<Dart_handle_2,Dart_handle>::iterator
         dartmap_iter, dartmap_iter_end=origin_to_copy->end();
       for (dartmap_iter=origin_to_copy->begin(); dartmap_iter!=dartmap_iter_end;
            ++dartmap_iter)
@@ -323,9 +322,9 @@ namespace CGAL {
     template<typename CMap2, typename Converters, typename DartInfoConverter,
              typename PointConverter>
     void copy(CMap2& amap,
-              boost::unordered_map
+              std::unordered_map
               <typename CMap2::Dart_handle, Dart_handle>* origin_to_copy,
-              boost::unordered_map
+              std::unordered_map
               <Dart_handle, typename CMap2::Dart_handle>* copy_to_origin,
               const Converters& converters,
               const DartInfoConverter& dartinfoconverter,
@@ -344,9 +343,9 @@ namespace CGAL {
     template<typename CMap2, typename Converters, typename DartInfoConverter,
              typename PointConverter>
     void copy_from_const(const CMap2& amap,
-                         boost::unordered_map
+                         std::unordered_map
                          <typename CMap2::Dart_const_handle, Dart_handle>* origin_to_copy,
-                         boost::unordered_map
+                         std::unordered_map
                          <Dart_handle, typename CMap2::Dart_const_handle>* copy_to_origin,
                          const Converters& converters,
                          const DartInfoConverter& dartinfoconverter,
@@ -364,9 +363,9 @@ namespace CGAL {
     // (2a) copy(amap, converters, dartinfoconverter)
     template<typename CMap2, typename Converters, typename DartInfoConverter>
     void copy(CMap2& amap,
-              boost::unordered_map
+              std::unordered_map
               <typename CMap2::Dart_handle, Dart_handle>* origin_to_copy,
-              boost::unordered_map
+              std::unordered_map
               <Dart_handle, typename CMap2::Dart_handle>* copy_to_origin,
               const Converters& converters,
               const DartInfoConverter& dartinfoconverter,
@@ -383,9 +382,9 @@ namespace CGAL {
     // (2b) copy_from_const(const amap, converters, dartinfoconverter)
     template <typename CMap2, typename Converters, typename DartInfoConverter>
     void copy_from_const(const CMap2& amap,
-                         boost::unordered_map
+                         std::unordered_map
                          <typename CMap2::Dart_const_handle, Dart_handle>* origin_to_copy,
-                         boost::unordered_map
+                         std::unordered_map
                          <Dart_handle, typename CMap2::Dart_const_handle>* copy_to_origin,
                          const Converters& converters,
                          const DartInfoConverter& dartinfoconverter,
@@ -402,9 +401,9 @@ namespace CGAL {
     // (3a) copy(amap, converters)
     template<typename CMap2, typename Converters>
     void copy(CMap2& amap,
-              boost::unordered_map
+              std::unordered_map
               <typename CMap2::Dart_handle, Dart_handle>* origin_to_copy,
-              boost::unordered_map
+              std::unordered_map
               <Dart_handle, typename CMap2::Dart_handle>* copy_to_origin,
               const Converters& converters,
               bool copy_perforated_darts=false,
@@ -418,9 +417,9 @@ namespace CGAL {
     // (3b) copy_from_const(const amap, converters)
     template <typename CMap2, typename Converters>
     void copy_from_const(const CMap2& amap,
-                         boost::unordered_map
+                         std::unordered_map
                          <typename CMap2::Dart_const_handle, Dart_handle>* origin_to_copy,
-                         boost::unordered_map
+                         std::unordered_map
                          <Dart_handle, typename CMap2::Dart_const_handle>* copy_to_origin,
                          const Converters& converters,
                          bool copy_perforated_darts=false,
@@ -434,9 +433,9 @@ namespace CGAL {
     // (4a) copy(amap)
     template<typename CMap2>
     void copy(CMap2& amap,
-              boost::unordered_map
+              std::unordered_map
               <typename CMap2::Dart_handle, Dart_handle>* origin_to_copy=nullptr,
-              boost::unordered_map
+              std::unordered_map
               <Dart_handle, typename CMap2::Dart_handle>* copy_to_origin=nullptr,
               bool copy_perforated_darts=false,
               size_type mark_perforated=INVALID_MARK)
@@ -449,9 +448,9 @@ namespace CGAL {
     // (4b) copy_from_const(const amap)
     template <typename CMap2>
     void copy_from_const(const CMap2& amap,
-                         boost::unordered_map
+                         std::unordered_map
                          <typename CMap2::Dart_const_handle, Dart_handle>* origin_to_copy=nullptr,
-                         boost::unordered_map
+                         std::unordered_map
                          <Dart_handle, typename CMap2::Dart_const_handle>* copy_to_origin=nullptr,
                          bool copy_perforated_darts=false,
                          size_type mark_perforated=INVALID_MARK)
@@ -555,10 +554,10 @@ namespace CGAL {
     /** Import the given hds which should be a model of an halfedge graph. */
     template<class HEG>
     void import_from_halfedge_graph(const HEG& heg,
-                                    boost::unordered_map
+                                    std::unordered_map
                                     <typename boost::graph_traits<HEG>::halfedge_descriptor,
                                     Dart_handle>* origin_to_copy=NULL,
-                                    boost::unordered_map
+                                    std::unordered_map
                                     <Dart_handle,
                                     typename boost::graph_traits<HEG>::halfedge_descriptor>*
                                     copy_to_origin=NULL,
@@ -568,7 +567,7 @@ namespace CGAL {
       // Create an mapping between darts of the two maps (originals->copies).
       // (here we cannot use CGAL::Unique_hash_map because it does not provide
       // iterators...
-      boost::unordered_map
+      std::unordered_map
         <typename boost::graph_traits<HEG>::halfedge_descriptor,
          Dart_handle> local_dartmap;
       if (origin_to_copy==NULL) // Used local_dartmap if user does not provides its own unordered_map
@@ -591,7 +590,7 @@ namespace CGAL {
         }
       }
 
-      typename boost::unordered_map
+      typename std::unordered_map
         <typename boost::graph_traits<HEG>::halfedge_descriptor,
          Dart_handle>::iterator dartmap_iter, dartmap_iter_end=origin_to_copy->end();
       for (dartmap_iter=origin_to_copy->begin(); dartmap_iter!=dartmap_iter_end;
diff --git a/Generalized_map/include/CGAL/Generalized_map.h b/Generalized_map/include/CGAL/Generalized_map.h
index ad8de549631..31623b6fbeb 100644
--- a/Generalized_map/include/CGAL/Generalized_map.h
+++ b/Generalized_map/include/CGAL/Generalized_map.h
@@ -196,8 +196,8 @@ namespace CGAL {
               typename Converters, typename DartInfoConverter,
               typename PointConverter>
     void generic_copy(GMap2& amap,
-                      boost::unordered_map<Dart_handle_2, Dart_handle>* origin_to_copy,
-                      boost::unordered_map<Dart_handle, Dart_handle_2>* copy_to_origin,
+                      std::unordered_map<Dart_handle_2, Dart_handle>* origin_to_copy,
+                      std::unordered_map<Dart_handle, Dart_handle_2>* copy_to_origin,
                       const Converters& converters,
                       const DartInfoConverter& dartinfoconverter,
                       const PointConverter& pointconverter,
@@ -223,7 +223,7 @@ namespace CGAL {
       // Create an mapping between darts of the two maps (originals->copies).
       // (here we cannot use CGAL::Unique_hash_map because it does not provide
       // iterators...
-      boost::unordered_map<Dart_handle_2, Dart_handle> local_dartmap;
+      std::unordered_map<Dart_handle_2, Dart_handle> local_dartmap;
       if (origin_to_copy==NULL) // Use local_dartmap if user does not provides its own unordered_map
       { origin_to_copy=&local_dartmap; }
 
@@ -251,7 +251,7 @@ namespace CGAL {
 
       unsigned int min_dim=(dimension<amap.dimension?dimension:amap.dimension);
 
-      typename boost::unordered_map<Dart_handle_2, Dart_handle>::iterator
+      typename std::unordered_map<Dart_handle_2, Dart_handle>::iterator
         dartmap_iter, dartmap_iter_end=origin_to_copy->end();
       for (dartmap_iter=origin_to_copy->begin(); dartmap_iter!=dartmap_iter_end;
            ++dartmap_iter)
@@ -286,9 +286,9 @@ namespace CGAL {
     template<typename GMap2, typename Converters, typename DartInfoConverter,
              typename PointConverter>
     void copy(GMap2& amap,
-              boost::unordered_map
+              std::unordered_map
               <typename GMap2::Dart_handle, Dart_handle>* origin_to_copy,
-              boost::unordered_map
+              std::unordered_map
               <Dart_handle, typename GMap2::Dart_handle>* copy_to_origin,
               const Converters& converters,
               const DartInfoConverter& dartinfoconverter,
@@ -307,9 +307,9 @@ namespace CGAL {
     template<typename GMap2, typename Converters, typename DartInfoConverter,
              typename PointConverter>
     void copy_from_const(const GMap2& amap,
-                         boost::unordered_map
+                         std::unordered_map
                          <typename GMap2::Dart_const_handle, Dart_handle>* origin_to_copy,
-                         boost::unordered_map
+                         std::unordered_map
                          <Dart_handle, typename GMap2::Dart_const_handle>* copy_to_origin,
                          const Converters& converters,
                          const DartInfoConverter& dartinfoconverter,
@@ -327,9 +327,9 @@ namespace CGAL {
     // (2a) copy(amap, converters, dartinfoconverter)
     template<typename GMap2, typename Converters, typename DartInfoConverter>
     void copy(GMap2& amap,
-              boost::unordered_map
+              std::unordered_map
               <typename GMap2::Dart_handle, Dart_handle>* origin_to_copy,
-              boost::unordered_map
+              std::unordered_map
               <Dart_handle, typename GMap2::Dart_handle>* copy_to_origin,
               const Converters& converters,
               const DartInfoConverter& dartinfoconverter,
@@ -346,9 +346,9 @@ namespace CGAL {
     // (2b) copy_from_const(const amap, converters, dartinfoconverter)
     template <typename GMap2, typename Converters, typename DartInfoConverter>
     void copy_from_const(const GMap2& amap,
-                         boost::unordered_map
+                         std::unordered_map
                          <typename GMap2::Dart_const_handle, Dart_handle>* origin_to_copy,
-                         boost::unordered_map
+                         std::unordered_map
                          <Dart_handle, typename GMap2::Dart_const_handle>* copy_to_origin,
                          const Converters& converters,
                          const DartInfoConverter& dartinfoconverter,
@@ -365,9 +365,9 @@ namespace CGAL {
     // (3a) copy(amap, converters)
     template<typename GMap2, typename Converters>
     void copy(GMap2& amap,
-              boost::unordered_map
+              std::unordered_map
               <typename GMap2::Dart_handle, Dart_handle>* origin_to_copy,
-              boost::unordered_map
+              std::unordered_map
               <Dart_handle, typename GMap2::Dart_handle>* copy_to_origin,
               const Converters& converters,
               bool copy_perforated_darts=false,
@@ -381,9 +381,9 @@ namespace CGAL {
     // (3b) copy_from_const(const amap, converters)
     template <typename GMap2, typename Converters>
     void copy_from_const(const GMap2& amap,
-                         boost::unordered_map
+                         std::unordered_map
                          <typename GMap2::Dart_const_handle, Dart_handle>* origin_to_copy,
-                         boost::unordered_map
+                         std::unordered_map
                          <Dart_handle, typename GMap2::Dart_const_handle>* copy_to_origin,
                          const Converters& converters,
                          bool copy_perforated_darts=false,
@@ -397,9 +397,9 @@ namespace CGAL {
     // (4a) copy(amap)
     template<typename GMap2>
     void copy(GMap2& amap,
-              boost::unordered_map
+              std::unordered_map
               <typename GMap2::Dart_handle, Dart_handle>* origin_to_copy=nullptr,
-              boost::unordered_map
+              std::unordered_map
               <Dart_handle, typename GMap2::Dart_handle>* copy_to_origin=nullptr,
               bool copy_perforated_darts=false,
               size_type mark_perforated=INVALID_MARK)
@@ -412,9 +412,9 @@ namespace CGAL {
     // (4b) copy_from_const(const amap)
     template <typename GMap2>
     void copy_from_const(const GMap2& amap,
-                         boost::unordered_map
+                         std::unordered_map
                          <typename GMap2::Dart_const_handle, Dart_handle>* origin_to_copy=nullptr,
-                         boost::unordered_map
+                         std::unordered_map
                          <Dart_handle, typename GMap2::Dart_const_handle>* copy_to_origin=nullptr,
                          bool copy_perforated_darts=false,
                          size_type mark_perforated=INVALID_MARK)
diff --git a/Linear_cell_complex/include/CGAL/Linear_cell_complex_for_combinatorial_map.h b/Linear_cell_complex/include/CGAL/Linear_cell_complex_for_combinatorial_map.h
index b1761257ab1..848951d424d 100644
--- a/Linear_cell_complex/include/CGAL/Linear_cell_complex_for_combinatorial_map.h
+++ b/Linear_cell_complex/include/CGAL/Linear_cell_complex_for_combinatorial_map.h
@@ -19,6 +19,7 @@
 #include <CGAL/Combinatorial_map.h>
 #include <CGAL/CMap_linear_cell_complex_storages.h>
 #include <CGAL/boost/graph/properties.h>
+#include <unordered_map>
 
 namespace CGAL {
 
@@ -162,16 +163,16 @@ namespace CGAL {
       template<class HEG, class PointConverter>
       void import_from_halfedge_graph(const HEG& heg              ,
                                       const PointConverter& pointconverter,
-                                      boost::unordered_map
+                                      std::unordered_map
                                       <typename boost::graph_traits<HEG>::halfedge_descriptor,
                                       Dart_handle>* origin_to_copy=NULL,
-                                      boost::unordered_map
+                                      std::unordered_map
                                       <Dart_handle,
                                       typename boost::graph_traits<HEG>::halfedge_descriptor>*
                                       copy_to_origin=NULL)
 
       {
-        boost::unordered_map
+        std::unordered_map
             <typename boost::graph_traits<HEG>::halfedge_descriptor,
             Dart_handle> local_dartmap;
         if (origin_to_copy==NULL) // Used local_dartmap if user does not provides its own unordered_map
@@ -183,7 +184,7 @@ namespace CGAL {
             Point_property_map;
         Point_property_map ppmap = get(CGAL::vertex_point, heg);
 
-        typename boost::unordered_map
+        typename std::unordered_map
           <typename boost::graph_traits<HEG>::halfedge_descriptor,
            Dart_handle>::iterator dartmap_iter, dartmap_iter_end=origin_to_copy->end();
         for (dartmap_iter=origin_to_copy->begin(); dartmap_iter!=dartmap_iter_end;
@@ -202,10 +203,10 @@ namespace CGAL {
       /** Import the given hds which should be a model of an halfedge graph. */
       template<class HEG>
       void import_from_halfedge_graph(const HEG& heg,
-                                      boost::unordered_map
+                                      std::unordered_map
                                       <typename boost::graph_traits<HEG>::halfedge_descriptor,
                                       Dart_handle>* origin_to_copy=NULL,
-                                      boost::unordered_map
+                                      std::unordered_map
                                       <Dart_handle,
                                       typename boost::graph_traits<HEG>::halfedge_descriptor>*
                                       copy_to_origin=NULL)
diff --git a/Surface_mesh_topology/examples/Surface_mesh_topology/unsew_edgewidth_repeatedly.cpp b/Surface_mesh_topology/examples/Surface_mesh_topology/unsew_edgewidth_repeatedly.cpp
index 47c1d952004..5c18a4a0ec2 100644
--- a/Surface_mesh_topology/examples/Surface_mesh_topology/unsew_edgewidth_repeatedly.cpp
+++ b/Surface_mesh_topology/examples/Surface_mesh_topology/unsew_edgewidth_repeatedly.cpp
@@ -8,7 +8,7 @@
 #include <iostream>
 #include <fstream>
 #include <cstdlib>
-#include <unordered_set>
+#include <unordered_map>
 
 using LCC_3            =CGAL::Linear_cell_complex_for_generalized_map<2, 3>;
 using Dart_handle      =LCC_3::Dart_handle;
@@ -97,7 +97,7 @@ int main(int argc, char* argv[])
   CGAL::load_off(lccoriginal, inp);
   std::cout<<"File '"<<filename<<"' loaded. Running the main program..."<<std::endl;
 
-  boost::unordered_map<Dart_handle, Dart_handle> origin_to_copy;
+  std::unordered_map<Dart_handle, Dart_handle> origin_to_copy;
   lcccopy.copy(lccoriginal, &origin_to_copy, nullptr);
 
   LCC_3::size_type is_root=lccoriginal.get_new_mark();
diff --git a/Surface_mesh_topology/include/CGAL/Surface_mesh_topology/internal/Generic_map_selector.h b/Surface_mesh_topology/include/CGAL/Surface_mesh_topology/internal/Generic_map_selector.h
index fcc5322c084..b8deff441ef 100644
--- a/Surface_mesh_topology/include/CGAL/Surface_mesh_topology/internal/Generic_map_selector.h
+++ b/Surface_mesh_topology/include/CGAL/Surface_mesh_topology/internal/Generic_map_selector.h
@@ -44,9 +44,9 @@ namespace internal {
     using Mesh_original              = Mesh_;
     using Generic_map                = CGAL::Generalized_map<2, Items_>;
     using Dart_const_handle_original = typename Mesh_original::Dart_const_handle;
-    using Copy_to_origin_map         = boost::unordered_map<typename Generic_map::Dart_handle,
+    using Copy_to_origin_map         = std::unordered_map<typename Generic_map::Dart_handle,
                                                             Dart_const_handle_original>;
-    using Origin_to_copy_map         = boost::unordered_map<Dart_const_handle_original,
+    using Origin_to_copy_map         = std::unordered_map<Dart_const_handle_original,
                                                             typename Generic_map::Dart_handle>;
 
     static void copy(Generic_map& target, const Mesh_original& source,
@@ -64,9 +64,9 @@ namespace internal {
     using Mesh_original              = Mesh_;
     using Generic_map                = CGAL::Combinatorial_map<2, Items_>;
     using Dart_const_handle_original = typename Mesh_original::Dart_const_handle;
-    using Copy_to_origin_map         = boost::unordered_map<typename Generic_map::Dart_handle,
+    using Copy_to_origin_map         = std::unordered_map<typename Generic_map::Dart_handle,
                                                             Dart_const_handle_original>;
-    using Origin_to_copy_map         = boost::unordered_map<Dart_const_handle_original,
+    using Origin_to_copy_map         = std::unordered_map<Dart_const_handle_original,
                                                             typename Generic_map::Dart_handle>;
 
     static void copy(Generic_map& target, const Mesh_original& source,
@@ -83,9 +83,9 @@ namespace internal {
     using Mesh_original              = Mesh_;
     using Generic_map                = CGAL::Combinatorial_map<2, Items_>;
     using Dart_const_handle_original = typename boost::graph_traits<Mesh_original>::halfedge_descriptor;
-    using Copy_to_origin_map         = boost::unordered_map<typename Generic_map::Dart_handle,
+    using Copy_to_origin_map         = std::unordered_map<typename Generic_map::Dart_handle,
                                                             Dart_const_handle_original>;
-    using Origin_to_copy_map         = boost::unordered_map<Dart_const_handle_original,
+    using Origin_to_copy_map         = std::unordered_map<Dart_const_handle_original,
                                                             typename Generic_map::Dart_handle>;
 
     static void copy(Generic_map& target, const Mesh_original& source,
diff --git a/Surface_mesh_topology/include/CGAL/Surface_mesh_topology/internal/Shortest_noncontractible_cycle.h b/Surface_mesh_topology/include/CGAL/Surface_mesh_topology/internal/Shortest_noncontractible_cycle.h
index fd5fbb83d0d..a233c29b22f 100644
--- a/Surface_mesh_topology/include/CGAL/Surface_mesh_topology/internal/Shortest_noncontractible_cycle.h
+++ b/Surface_mesh_topology/include/CGAL/Surface_mesh_topology/internal/Shortest_noncontractible_cycle.h
@@ -65,8 +65,8 @@ public:
   using Path          =CGAL::Surface_mesh_topology::Path_on_surface<Mesh>;
 
   // Associations between original darts and their copy.
-  using Origin_to_copy=boost::unordered_map<Original_dart_const_handle, Dart_handle>;
-  using Copy_to_origin=boost::unordered_map<Dart_handle, Original_dart_const_handle>;
+  using Origin_to_copy=std::unordered_map<Original_dart_const_handle, Dart_handle>;
+  using Copy_to_origin=std::unordered_map<Dart_handle, Original_dart_const_handle>;
 
   /// @return the local map
   const Local_map& get_local_map() const