diff --git a/index.html b/index.html
index d0efbb0a..0562f0db 100644
--- a/index.html
+++ b/index.html
@@ -7855,6 +7855,7 @@
   <script src="modules/military-generator.js"></script>
   <script src="modules/markers-generator.js"></script>
   <script src="modules/coa-generator.js"></script>
+  <script src="modules/submap.js"></script>
   <script src="libs/polylabel.min.js"></script>
   <script src="libs/lineclip.min.js"></script>
   <script src="libs/jquery-ui.min.js"></script>
diff --git a/modules/river-generator.js b/modules/river-generator.js
index 08500534..957fe6fc 100644
--- a/modules/river-generator.js
+++ b/modules/river-generator.js
@@ -40,6 +40,7 @@ window.Rivers = (function () {
       const cellsNumberModifier = (pointsInput.dataset.cells / 10000) ** 0.25;
 
       const prec = grid.cells.prec;
+      const area = pack.cells.area;
       const land = cells.i.filter(i => h[i] >= 20).sort((a, b) => h[b] - h[a]);
       const lakeOutCells = Lakes.setClimateData(h);
 
diff --git a/utils/arrayUtils.js b/utils/arrayUtils.js
index 06f0448c..a466a0b7 100644
--- a/utils/arrayUtils.js
+++ b/utils/arrayUtils.js
@@ -62,3 +62,37 @@ function createTypedArray({maxValue, length, from}) {
 function unique(array) {
   return [...new Set(array)];
 }
+
+// deep copy for Arrays (and other objects)
+function deepCopy(obj) {
+  const id = x=>x;
+  const dcTArray = a => a.map(id);
+  const dcObject = x => Object.fromEntries(Object.entries(x).map(([k,d])=>[k,dcAny(d)]));
+  const dcAny = x => x instanceof Object ? (cf.get(x.constructor)||id)(x) : x;
+  // don't map keys, probably this is what we would expect
+  const dcMapCore = m => [...m.entries()].map(([k,v])=>[k, dcAny(v)]);
+
+  const cf = new Map([
+      [Int8Array, dcTArray],
+      [Uint8Array, dcTArray],
+      [Uint8ClampedArray, dcTArray],
+      [Int16Array, dcTArray],
+      [Uint16Array, dcTArray],
+      [Int32Array, dcTArray],
+      [Uint32Array, dcTArray],
+      [Float32Array, dcTArray],
+      [Float64Array, dcTArray],
+      [BigInt64Array, dcTArray],
+      [BigUint64Array, dcTArray],
+      [Map, m => new Map(dcMapCore(m))],
+      [WeakMap, m => new WeakMap(dcMapCore(m))],
+      [Array, a => a.map(dcAny)],
+      [Set, s => [...s.values()].map(dcAny)],
+      [Date, d => new Date(d.getTime())],
+      [Object, dcObject],
+      // other types will be referenced
+      // ... extend here to implement their custom deep copy
+  ]);
+
+  return dcAny(obj);
+}