A diving device is a tool used by divers to explore underwater environments. Bathysphere, which has 11 letters, is a type of diving device that is a spherical submersible vessel used for deep sea exploration. SCUBA, with 5 letters, is an acronym for Self-Contained Underwater Breathing Apparatus, which is a type of diving device that provides the diver with air from a tank. Lastly, snorkel, with 7 letters, is a type of diving device that is a tube used to breathe at the surface while the diver's face is submerged.