Deep Dome is the deepest of two levels of Deep Hole. Within it, you will find, most notably, a cave blocked off by a pile of rocky rubble. When you move this rubble with the help of a dolphin partner (from a saltwater area), you will release a trapped Pygmy Sperm Whale. Along with this, a multitude of Pineconefish and a few Singular Bannerfish (under zoom-mode spots) can be found as well. On the level above this one, the entrance to Deep Dome isn't the only entrance to a cave; the entrances to the Serpent's Lair and Giant's Grotto are here as well.