Obviously they’ll be a little tough to get to unless you build up to them but be sure you go there armed. There’s a dungeon on every one and once you defeat the mobs you can reap the spoils in a chest below the spawner.
The best part about this mod is the randomization of the islands. You won’t know where they turn up or what type of mob is contained within each dungeon. Plus the random chest loot could highly benefit you.