Bathysphere

A bathysphere is a spherical steel deep-sea submersible, lowered into the water on a cable rather than propelling itself, designed to let observers descend far below the surface while withstanding the enormous pressure of the deep ocean. American engineer Otis Barton designed and built the bathysphere, and naturalist William Beebe used it for a series of record dives off the coast of Bermuda beginning in 1930, reaching a depth of 3,028 feet in 1934, a record for human ocean descent that stood for years. The bathysphere's thick-walled spherical shape and small fused-quartz viewing windows became a model for later deep-sea observation vehicles.