Some island stuff came to my mind recently
-Special fires that could be used to forge weapons,armor only usable with a new blacksmith profession or locked behind
puppys mentioned nests
-Ancient mazes with traps that gets bigger as you go by further into dark sea for also they will be under the islands and mazes will change shape everytime you go in dark sea for loot make it variable rooms a potion room with catalyst and reagents includes a guaranteed golden cauldron or 5 guaranteed legendary catalyst,a special fire forge room etc.
-Chest Mimics that can become any type of chests
-Ents