diff --git a/src/main/java/world/bentobox/bentobox/managers/island/IslandCache.java b/src/main/java/world/bentobox/bentobox/managers/island/IslandCache.java
index acfdabc8f..f5edc3c8f 100644
--- a/src/main/java/world/bentobox/bentobox/managers/island/IslandCache.java
+++ b/src/main/java/world/bentobox/bentobox/managers/island/IslandCache.java
@@ -445,7 +445,7 @@ public class IslandCache {
     }
 
     /**
-     * Get the island by unique id
+     * Get the island by unique id. The Island will be cached if it is not already.
      * 
      * @param uniqueId unique id of the Island.
      * @return island or null if none found
@@ -479,6 +479,16 @@ public class IslandCache {
         return island;
     }
 
+    /**
+     * Removes the island from the cache to ensure it is reloaded from the database next time.
+     * @param uniqueId unique id of the Island.
+     * @return true if the island was in the cache, false otherwise.
+     * @since 2.4.1
+     */
+    public boolean expireIslandById(@NonNull String uniqueId) {
+        return islandsById.containsKey(uniqueId) && islandsById.put(uniqueId, null) != null;
+    }
+
     /**
      * Place the island into the cache map 
      * @param island island
@@ -540,4 +550,13 @@ public class IslandCache {
         return this.islandsById.containsKey(uniqueId);
     }
 
+    /**
+     * Returns if this island is cached. 
+     * @param uniqueId - unique id of island
+     * @return true if this island is caches, false if not, or if the island is unknown
+     */
+    public boolean isIslandCached(String uniqueId) {
+        return islandsById.get(uniqueId) != null;
+    }
+
 }
diff --git a/src/main/java/world/bentobox/bentobox/managers/island/IslandGrid.java b/src/main/java/world/bentobox/bentobox/managers/island/IslandGrid.java
index 0893a7f09..d7d7b2c43 100644
--- a/src/main/java/world/bentobox/bentobox/managers/island/IslandGrid.java
+++ b/src/main/java/world/bentobox/bentobox/managers/island/IslandGrid.java
@@ -1,6 +1,7 @@
 package world.bentobox.bentobox.managers.island;
 
 import java.util.Map.Entry;
+
 import java.util.TreeMap;
 
 import world.bentobox.bentobox.database.objects.Island;
@@ -33,8 +34,10 @@ class IslandGrid {
             TreeMap<Integer, String> zEntry = grid.get(island.getMinX());
             if (zEntry.containsKey(island.getMinZ())) {
                 if (island.getUniqueId().equals(zEntry.get(island.getMinZ()))) {
+                    // If it is the same island then it's okay
                     return true;
                 }
+                // Island overlap, report error
                 return false;
             } else {
                 // Add island
diff --git a/src/test/java/world/bentobox/bentobox/managers/island/IslandCacheTest.java b/src/test/java/world/bentobox/bentobox/managers/island/IslandCacheTest.java
index 2a8410ec7..f99961a4f 100644
--- a/src/test/java/world/bentobox/bentobox/managers/island/IslandCacheTest.java
+++ b/src/test/java/world/bentobox/bentobox/managers/island/IslandCacheTest.java
@@ -140,7 +140,7 @@ public class IslandCacheTest extends AbstractCommonSetup {
 
         // database must be mocked here
         db = mock(Database.class);
-        when(db.loadObject(anyString())).thenReturn(island);
+        when(db.loadObject("uniqueId")).thenReturn(island);
         when(db.saveObjectAsync(any())).thenReturn(CompletableFuture.completedFuture(true));
 
         // New cache
@@ -346,9 +346,13 @@ public class IslandCacheTest extends AbstractCommonSetup {
         // Fill the cache
         ic.addIsland(island);
         ic.setIslandById(island);
+        assertTrue(ic.isIslandCached("uniqueId"));
+
         // Remove it
         ic.deleteIslandFromCache(island);
-        // TODO need to verify
+
+        // verify
+        assertFalse(ic.isIslandCached("uniqueId"));
     }
 
     /**
@@ -466,4 +470,147 @@ public class IslandCacheTest extends AbstractCommonSetup {
         assertTrue(ic.getIslands(owner).isEmpty());
     }
 
+    /**
+     * Test method for {@link world.bentobox.bentobox.managers.island.IslandCache#addIsland(world.bentobox.bentobox.database.objects.Island)}.
+     */
+    @Test
+    public void testAddIslandIslandNullWorld() {
+        // Null world
+        when(island.getWorld()).thenReturn(null);
+        assertFalse(ic.addIsland(island));
+    }
+
+    /**
+     * Test method for {@link world.bentobox.bentobox.managers.island.IslandCache#addIsland(world.bentobox.bentobox.database.objects.Island)}.
+     */
+    @Test
+    public void testAddIslandIslandNullCenter() {
+        // Try to add an island with a null center
+        when(island.getCenter()).thenReturn(null);
+        assertFalse(ic.addIsland(island));
+    }
+
+    /**
+     * Test method for {@link world.bentobox.bentobox.managers.island.IslandCache#addIsland(world.bentobox.bentobox.database.objects.Island)}.
+     */
+    @Test
+    public void testAddIslandIslandDuplicate() {
+        assertTrue(ic.addIsland(island));
+        assertTrue(ic.addIsland(island)); // Okay to add
+    }
+
+    /**
+     * Test method for {@link world.bentobox.bentobox.managers.island.IslandCache#addIsland(world.bentobox.bentobox.database.objects.Island, boolean)}.
+     */
+    @Test
+    public void testAddIslandIslandBooleanNullWorld() {
+        // Null world
+        when(island.getWorld()).thenReturn(null);
+        assertFalse(ic.addIsland(island, true));
+        assertFalse(ic.isIslandCached("uniqueId"));
+    }
+
+    /**
+     * Test method for {@link world.bentobox.bentobox.managers.island.IslandCache#addIsland(world.bentobox.bentobox.database.objects.Island, boolean)}.
+     */
+    @Test
+    public void testAddIslandIslandBooleanNullCenter() {
+        // Try to add an island with a null center
+        when(island.getCenter()).thenReturn(null);
+        assertFalse(ic.addIsland(island, true));
+        assertFalse(ic.isIslandCached("uniqueId"));
+    }
+
+    /**
+     * Test method for {@link world.bentobox.bentobox.managers.island.IslandCache#addIsland(world.bentobox.bentobox.database.objects.Island, boolean)}.
+     */
+    @Test
+    public void testAddIslandIslandBooleanDuplicate() {
+        // Duplicate
+        assertTrue(ic.addIsland(island, true));
+        assertTrue(ic.addIsland(island, true));
+        // Overlapping
+        Island island2 = mock(Island.class);
+        when(island2.getUniqueId()).thenReturn("different");
+        assertFalse(ic.addIsland(island2, true));
+    }
+
+
+    /**
+     * Test method for {@link world.bentobox.bentobox.managers.island.IslandCache#loadIsland(java.lang.String)}.
+     */
+    @Test
+    public void testLoadIsland() {
+        assertNull(ic.loadIsland(""));
+        assertNotNull(ic.loadIsland("uniqueId"));
+    }
+
+    /**
+     * Test method for {@link world.bentobox.bentobox.managers.island.IslandCache#getCachedIslands()}.
+     */
+    @Test
+    public void testGetCachedIslands() {
+        assertTrue(ic.getCachedIslands().isEmpty());
+    }
+
+    /**
+     * Test method for {@link world.bentobox.bentobox.managers.island.IslandCache#getIslandById(java.lang.String)}.
+     */
+    @Test
+    public void testGetIslandByIdString() {
+        assertNotNull(ic.getIslandById("uniqueId"));
+        assertTrue(ic.isIslandCached("uniqueId"));
+    }
+
+    /**
+     * Test method for {@link world.bentobox.bentobox.managers.island.IslandCache#getIslandById(java.lang.String, boolean)}.
+     */
+    @Test
+    public void testGetIslandByIdStringBoolean() {
+        assertNotNull(ic.getIslandById("uniqueId", false));
+        assertFalse(ic.isIslandCached("uniqueId"));
+    }
+
+    /**
+     * Test method for {@link world.bentobox.bentobox.managers.island.IslandCache#expireIslandById(java.lang.String)}.
+     */
+    @Test
+    public void testExpireIslandById() {
+        // Fill the cache
+        ic.addIsland(island);
+        ic.setIslandById(island);
+        assertTrue(ic.isIslandCached("uniqueId"));
+        // Remove it
+        ic.expireIslandById("uniqueId");
+        // verify
+        assertFalse(ic.isIslandCached("uniqueId"));
+
+    }
+
+    /**
+     * Test method for {@link world.bentobox.bentobox.managers.island.IslandCache#setIslandById(world.bentobox.bentobox.database.objects.Island)}.
+     */
+    @Test
+    public void testSetIslandById() {
+        assertFalse(ic.isIslandId("uniqueId"));
+        ic.setIslandById(island);
+        assertTrue(ic.isIslandId("uniqueId"));
+    }
+
+    /**
+     * Test method for {@link world.bentobox.bentobox.managers.island.IslandCache#isIslandId(java.lang.String)}.
+     */
+    @Test
+    public void testIsIslandId() {
+        assertFalse(ic.isIslandId("uniqueId"));
+    }
+
+    /**
+     * Test method for {@link world.bentobox.bentobox.managers.island.IslandCache#isIslandCached(java.lang.String)}.
+     */
+    @Test
+    public void testIsIslandCached() {
+        assertFalse(ic.isIslandCached("uniqueId"));
+    }
+
 }