diff --git a/src/TerraSharp/Core/Hotkeys.cs b/src/TerraSharp/Core/Hotkeys.cs
index cbe6467..9987a49 100644
--- a/src/TerraSharp/Core/Hotkeys.cs
+++ b/src/TerraSharp/Core/Hotkeys.cs
@@ -76,6 +76,7 @@ public static class Hotkeys
         Toggle("World", "FreezeTime", "Freeze Time", () => Settings.FreezeTime, v => Settings.FreezeTime = v),
         Toggle("World", "SpawnRate", "Spawn Rate", () => Settings.SpawnRateBoost, v => Settings.SpawnRateBoost = v),
         new("World", "SavePosition", "Save Current Position", Waypoints.AddHere),
+        new("World", "RevealMap", "Reveal Map", MapFeatures.StartReveal),
     ];
 
     // Windows virtual-key codes for mouse buttons; XNA's Keys leaves them unassigned.
diff --git a/src/TerraSharp/Features/MapFeatures.cs b/src/TerraSharp/Features/MapFeatures.cs
new file mode 100644
index 0000000..ea97b61
--- /dev/null
+++ b/src/TerraSharp/Features/MapFeatures.cs
@@ -0,0 +1,48 @@
+using System;
+using Terraria;
+
+namespace TerraSharp.Features;
+
+public static class MapFeatures
+{
+    const int ColumnsPerTick = 24;
+
+    // MapHelper.GetBackgroundType samples map tiles up to 36 away; WorldMap.UnlockMapSection keeps the same margin.
+    const int Margin = 40;
+
+    static int _revealColumn = -1;
+
+    public static bool Revealing => _revealColumn >= 0;
+
+    public static float RevealProgress => Revealing ? (_revealColumn - Margin) / (float)(Main.maxTilesX - 2 * Margin) : 0f;
+
+    public static void StartReveal() => _revealColumn = Margin;
+
+    // Main.DoUpdate postfix.
+    public static void Update()
+    {
+        if (Main.gameMenu)
+        {
+            _revealColumn = -1;
+            return;
+        }
+
+        RevealStep();
+    }
+
+    // A large world is about 20 million map tiles, so the reveal is spread over ticks.
+    static void RevealStep()
+    {
+        if (_revealColumn < 0)
+            return;
+
+        int start = _revealColumn, end = Math.Min(Main.maxTilesX - Margin, start + ColumnsPerTick);
+        _revealColumn = end < Main.maxTilesX - Margin ? end : -1;
+        for (int x = start; x < end; x++)
+            for (int y = Margin; y < Main.maxTilesY - Margin; y++)
+                Main.Map.Update(x, y, byte.MaxValue);
+
+        if (_revealColumn < 0)
+            Main.refreshMap = true;
+    }
+}
diff --git a/src/TerraSharp/Patches/MainPatches.cs b/src/TerraSharp/Patches/MainPatches.cs
index 5f44888..58fa809 100644
--- a/src/TerraSharp/Patches/MainPatches.cs
+++ b/src/TerraSharp/Patches/MainPatches.cs
@@ -44,6 +44,7 @@ internal static class MainUpdatePatch
         Hotkeys.Update();
         Sandbox.NewTick();
         WorldFeatures.Update();
+        MapFeatures.Update();
         Settings.AutoSave();
         Profiler.EndTick();
     }
diff --git a/src/TerraSharp/UI/MainWindow.Pages.cs b/src/TerraSharp/UI/MainWindow.Pages.cs
index 6ea1c47..436b957 100644
--- a/src/TerraSharp/UI/MainWindow.Pages.cs
+++ b/src/TerraSharp/UI/MainWindow.Pages.cs
@@ -251,6 +251,10 @@ public sealed partial class MainWindow
         if (WorldFeatures.InvasionName is { } active && Buttons($"Stop {active}") == 0)
             WorldFeatures.StopInvasion();
 
+        Group("Map");
+        if (Buttons(MapFeatures.Revealing ? $"Revealing... {MapFeatures.RevealProgress:0%}" : "Reveal Map") == 0 && !MapFeatures.Revealing)
+            MapFeatures.StartReveal();
+
         Group("Spawning");
         Note(NpcSpawner.Multiplayer ? "Multiplayer: boss summons only, spawn rate is ignored." : "Spawn rate only affects single player.");
         if (Toggle("Spawn Rate", ref Settings.SpawnRateBoost))
diff --git a/src/TerraSharp/UI/MainWindow.Tooltips.cs b/src/TerraSharp/UI/MainWindow.Tooltips.cs
index bdaf37d..537706f 100644
--- a/src/TerraSharp/UI/MainWindow.Tooltips.cs
+++ b/src/TerraSharp/UI/MainWindow.Tooltips.cs
@@ -57,6 +57,7 @@ public sealed partial class MainWindow
         ["Biome Sight"] = "Makes Corruption, Crimson and Hallow blocks glow.",
         ["Full Bright"] = "Lights everything at full brightness.",
         ["Extended Zoom"] = "Zoom in up to 8x and out until the edge of what the game draws.",
+        ["Reveal Map"] = "Reveals the whole map. Multiplayer only reveals areas the server has sent.",
         ["Full Heal"] = "Refills health and mana.",
         ["TP to Spawn"] = "Recalls like a Magic Mirror: to your bed if set, otherwise the world's spawn point.",
         ["Reset Learned Ballistics"] = "Clears learned projectile data. Learns it again as you shoot.",