diff --git a/src/core/game/GameMap.ts b/src/core/game/GameMap.ts
index 92689275b..292e3c47c 100644
--- a/src/core/game/GameMap.ts
+++ b/src/core/game/GameMap.ts
@@ -111,10 +111,16 @@ export class GameMapImpl implements GameMap {
   private readonly width_: number;
   private readonly height_: number;
 
-  // Lookup tables (LUTs) contain pre-computed values to avoid performing division at runtime
-  private readonly refToX: number[];
-  private readonly refToY: number[];
-  private readonly yToRef: number[];
+  // Lookup tables (LUTs) contain pre-computed values to avoid performing division at runtime.
+  // Typed arrays are used instead of plain JS Array to keep memory tight on large maps:
+  // Uint16Array uses 2 bytes/element vs ~8 bytes for a boxed number, saving ~53 MB on
+  // the Indian Subcontinent map (2000×2220 = 4.44 M tiles).
+  // Coordinates never exceed 65535 for any map in the game, so Uint16 is safe for x/y.
+  // yToRef stores tile refs (up to width*height-1) which can exceed 65535 for large maps,
+  // so it uses Int32Array.
+  private readonly refToX: Uint16Array;
+  private readonly refToY: Uint16Array;
+  private readonly yToRef: Int32Array;
 
   // Terrain bits (Uint8Array)
   private static readonly IS_LAND_BIT = 7;
@@ -148,11 +154,11 @@ export class GameMapImpl implements GameMap {
     this.height_ = height;
     this.terrain = terrainData;
     this.state = new Uint16Array(width * height);
-    // Precompute the LUTs
+    // Precompute the LUTs using typed arrays (see field declarations for rationale).
     let ref = 0;
-    this.refToX = new Array(width * height);
-    this.refToY = new Array(width * height);
-    this.yToRef = new Array(height);
+    this.refToX = new Uint16Array(width * height);
+    this.refToY = new Uint16Array(width * height);
+    this.yToRef = new Int32Array(height);
     for (let y = 0; y < height; y++) {
       this.yToRef[y] = ref;
       for (let x = 0; x < width; x++) {
diff --git a/src/core/pathfinding/algorithms/AStar.WaterHierarchical.ts b/src/core/pathfinding/algorithms/AStar.WaterHierarchical.ts
index 2958de79a..933804fbb 100644
--- a/src/core/pathfinding/algorithms/AStar.WaterHierarchical.ts
+++ b/src/core/pathfinding/algorithms/AStar.WaterHierarchical.ts
@@ -5,7 +5,6 @@ import { AbstractGraphAStar } from "./AStar.AbstractGraph";
 import { AStarWaterBounded } from "./AStar.WaterBounded";
 import { AbstractGraph, AbstractNode } from "./AbstractGraph";
 import { BFSGrid } from "./BFS.Grid";
-import { LAND_MARKER } from "./ConnectedComponents";
 
 export class AStarWaterHierarchical implements PathFinder<number> {
   private tileBFS: BFSGrid;
@@ -314,7 +313,7 @@ export class AStarWaterHierarchical implements PathFinder<number> {
       this.map.height(),
       tile,
       maxDistance,
-      (t: TileRef) => this.graph.getComponentId(t) !== LAND_MARKER,
+      (t: TileRef) => this.map.isWater(t),
       (t: TileRef, _dist: number) => {
         const tileX = this.map.x(t);
         const tileY = this.map.y(t);
diff --git a/tests/core/pathfinding/PathFinding.Water.test.ts b/tests/core/pathfinding/PathFinding.Water.test.ts
index 48d06b20f..fceef9764 100644
--- a/tests/core/pathfinding/PathFinding.Water.test.ts
+++ b/tests/core/pathfinding/PathFinding.Water.test.ts
@@ -12,6 +12,7 @@ import { createGame, L, W } from "./_fixtures";
 describe("PathFinding.Water", () => {
   let game: Game;
   let worldGame: Game;
+  let giantWorldGame: Game;
 
   function createPathFinder(g: Game = game): SteppingPathFinder<TileRef> {
     return PathFinding.Water(g);
@@ -20,6 +21,7 @@ describe("PathFinding.Water", () => {
   beforeAll(async () => {
     game = await setup("ocean_and_land");
     worldGame = await setup("world", { disableNavMesh: false });
+    giantWorldGame = await setup("giantworldmap", { disableNavMesh: false });
   });
 
   describe("findPath", () => {
@@ -274,4 +276,23 @@ describe("PathFinding.Water", () => {
       expect(path).not.toBeNull();
     });
   });
+
+  describe("Giant World Map routes", () => {
+    it("routes correctly in promoted components", () => {
+      const pathFinder = createPathFinder(giantWorldGame);
+      const map = giantWorldGame.map();
+
+      // Coordinates inside Component 459 in map4x (promoted)
+      const from = map.ref(2616, 452);
+      const to = map.ref(2676, 474);
+
+      expect(map.isWater(from)).toBe(true);
+      expect(map.isWater(to)).toBe(true);
+
+      const path = pathFinder.findPath(from, to);
+      expect(path).not.toBeNull();
+      expect(path![0]).toBe(from);
+      expect(path![path!.length - 1]).toBe(to);
+    });
+  });
 });