diff --git a/src/modules/geoportal/components/map-viewer.tsx b/src/modules/geoportal/components/map-viewer.tsx
index ea741c5..77a008c 100644
--- a/src/modules/geoportal/components/map-viewer.tsx
+++ b/src/modules/geoportal/components/map-viewer.tsx
@@ -53,7 +53,7 @@ const LAYER_IDS = {
 } as const;
 
 /** Basemap tile definitions */
-const BASEMAP_TILES: Record<BasemapId, { tiles: string[]; attribution: string; tileSize: number }> = {
+const BASEMAP_TILES: Record<BasemapId, { tiles: string[]; attribution: string; tileSize: number; maxzoom?: number }> = {
   osm: {
     tiles: [
       "https://a.tile.openstreetmap.org/{z}/{x}/{y}.png",
@@ -79,6 +79,7 @@ const BASEMAP_TILES: Record<BasemapId, { tiles: string[]; attribution: string; t
     attribution:
       '&copy; <a href="https://opentopomap.org">OpenTopoMap</a> (<a href="https://creativecommons.org/licenses/by-sa/3.0/">CC-BY-SA</a>)',
     tileSize: 256,
+    maxzoom: 17,
   },
 };
 
@@ -231,47 +232,7 @@ export const MapViewer = forwardRef<MapViewerHandle, MapViewerProps>(
       }
     }, [mapReady, layerVisibility, applyLayerVisibility]);
 
-    /* ---- Basemap switching ---- */
-    useEffect(() => {
-      const map = mapRef.current;
-      if (!map || !mapReady) return;
-
-      const source = map.getSource("basemap") as maplibregl.RasterTileSource | undefined;
-      if (!source) return;
-
-      const def = BASEMAP_TILES[basemap];
-      // Update tiles by re-adding the source
-      // MapLibre doesn't support changing tiles on existing source, so we rebuild
-      try {
-        // Remove all layers that depend on basemap source, then remove source
-        if (map.getLayer("basemap-tiles")) map.removeLayer("basemap-tiles");
-        map.removeSource("basemap");
-
-        map.addSource("basemap", {
-          type: "raster",
-          tiles: def.tiles,
-          tileSize: def.tileSize,
-          attribution: def.attribution,
-        });
-
-        // Re-add basemap layer at bottom
-        const firstLayerId = map.getStyle().layers[0]?.id;
-        map.addLayer(
-          {
-            id: "basemap-tiles",
-            type: "raster",
-            source: "basemap",
-            minzoom: 0,
-            maxzoom: 19,
-          },
-          firstLayerId // insert before first existing layer
-        );
-      } catch {
-        // Fallback: if anything fails, the map still works
-      }
-    }, [basemap, mapReady]);
-
-    /* ---- Map initialization ---- */
+    /* ---- Map initialization (recreates on basemap change) ---- */
     useEffect(() => {
       if (!containerRef.current) return;
 
@@ -295,13 +256,13 @@ export const MapViewer = forwardRef<MapViewerHandle, MapViewerProps>(
               type: "raster",
               source: "basemap",
               minzoom: 0,
-              maxzoom: 19,
+              maxzoom: initialBasemap.maxzoom ?? 19,
             },
           ],
         },
         center: center ?? DEFAULT_CENTER,
         zoom: zoom ?? DEFAULT_ZOOM,
-        maxZoom: 20,
+        maxZoom: initialBasemap.maxzoom ?? 20,
       });
 
       mapRef.current = map;
@@ -555,7 +516,7 @@ export const MapViewer = forwardRef<MapViewerHandle, MapViewerProps>(
         setMapReady(false);
       };
       // eslint-disable-next-line react-hooks/exhaustive-deps
-    }, [resolvedMartinUrl]);
+    }, [resolvedMartinUrl, basemap]);
 
     /* ---- Sync center/zoom prop changes ---- */
     useEffect(() => {