A submersible is a type of underwater vessel with limited mobility, intended to remain in one place during use. Submersibles are typically transported to their area of operation by surface ships or large submarines.

In general, submersibles differ from submarines in that submersibles typically have shorter range, and operate underwater almost exclusively, having little function at the surface. Many submersibles operate on a "tether" or "umbilical", remaining connected to a tender, (a submarine, surface vessel or platform).

A bathysphere is a type of submersible which lacks any self-propulsion. A predecessor of the bathysphere, the diving bell, consisted of a chamber, with an open bottom, lowered into the water.

The bathyscaphe is the predecessor to deep submergence vehicles, had less mobility that DSVs, but are untethered, and used something like a bathyshpere for a crew compartment.

Small unmanned submersibles called "marine remotely operated vehicles" or MROVs are widely used today to work in water too deep or too dangerous for divers.

Remotely operated vehicles (ROVs) repair offshore petroleum platforms and attach cables to sunken ships to hoist them. Such remotely operated vehicles are attached by a tether (a thick cable providing power and communications) to control center on a ship. Operators on the ship see video images sent back from the robot and may control its propellers and manipulator arm. The wreck of the Titanic was explored by such a vehicle, as well as by a manned vessel.

Among the most famous submersibles is the deep-submergence research vessel DSV Alvin.

See also

• Submarine