A diving bell is a rigid chamber used to transport divers from the surface to depth and back in open water, usually for the purpose of performing underwater work. The most common types are the open-bottomed wet bell and the closed bell, which can maintain an internal pressure greater than the external ambient. Diving bells are usually suspended by a cable, and lifted and lowered by a winch from a surface support platform. Unlike a submersible, the diving bell is not designed to move under the control of its occupants, or to operate independently of its launch and recovery system.
Exterior view of an open (wet) diving bell
16th century Islamic painting of Alexander the Great lowered in a glass diving bell
Open diving bell on a stern mounted launch and recovery system
Wet bell exterior view
A submersible is an underwater vehicle which needs to be transported and supported by a larger watercraft or platform. This distinguishes submersibles from submarines, which are self-supporting and capable of prolonged independent operation at sea.
Retired modern submersible Star III of Scripps Institution of Oceanography
Ictineu 3 is a crewed submersible with a large semi-spheric acrylic glass viewport and is capable of reaching depths of 1,200 m (3,900 ft).
