diff --git a/lib/type-mapper.js b/lib/type-mapper.js
index 6165b44..4be9ef0 100644
--- a/lib/type-mapper.js
+++ b/lib/type-mapper.js
@@ -7,6 +7,7 @@ const BOOLEAN = { type: 'boolean' };
 const INTEGER = { type: 'integer' };
 const NUMBER = { type: 'number' };
 const STRING = { type: 'string' };
+const GEOMETRY = { type: 'object' };
 const ANY = { anyOf: [OBJECT, ARRAY, BOOLEAN, INTEGER, NUMBER, STRING] };
 
 /**
@@ -186,9 +187,73 @@ class TypeMapper {
       // @todo GEOMETRY('POINT', 4326)
       // ----------------------------------------------------------------------
       case 'GEOMETRY': {
-        throw new TypeError(
-          'sequelize-to-json-schemas has not yet implemented the GEOMETRY DataType',
-        );
+        const geometrySubType = properties.type?.options?.type?.toUpperCase();
+
+        result = {
+          ...GEOMETRY,
+          required: ['type', 'coordinates'],
+          properties: {
+            type: {
+              type: 'string',
+              enum: geometrySubType
+                ? [geometrySubType[0] + geometrySubType.slice(1).toLowerCase()]
+                : [
+                  'Point',
+                  'LineString',
+                  'Polygon',
+                  'MultiPoint',
+                  'MultiLineString',
+                  'MultiPolygon',
+                  'GeometryCollection',
+                ],
+            },
+            coordinates: { type: 'array' }, // refined below
+          },
+        };
+
+        switch (geometrySubType) {
+          case 'POINT':
+            result.properties.coordinates = {
+              type: 'array',
+              items: { type: 'number' },
+              minItems: 2,
+            };
+            break;
+
+          case 'MULTIPOINT':
+          case 'LINESTRING':
+            result.properties.coordinates = {
+              type: 'array',
+              items: { type: 'array', items: { type: 'number' }, minItems: 2 },
+            };
+            break;
+
+          case 'MULTILINESTRING':
+          case 'POLYGON':
+            result.properties.coordinates = {
+              type: 'array',
+              items: {
+                type: 'array',
+                items: { type: 'array', items: { type: 'number' }, minItems: 2 },
+              },
+            };
+            break;
+
+          case 'MULTIPOLYGON':
+            result.properties.coordinates = {
+              type: 'array',
+              items: {
+                type: 'array',
+                items: {
+                  type: 'array',
+                  items: { type: 'array', items: { type: 'number' }, minItems: 2 },
+                },
+              },
+            };
+            break;
+        }
+
+        break;
       }
 
       // ----------------------------------------------------------------------