The Underwater Islands Caves are a cave system that can be found in some of the larger islands in the Underwater Islands biome.
It features upside-down Coral Shell Plates, Spotted Dockleafs, Rubies, and Cave Crawlers, who can be seen falling from the top to bottom. The entrance to the smallest of these caves can be found right next to the Underwater Islands Wreck. The larger of the caves can be found on a larger island nearby. These larger caves house more materials and a lot of Cave Crawlers. There are four entrances to this cave and three to the smaller one.