Submarine Escape Immersion Equipment (SEIE), also known as Submarine Escape and Immersion Equipment, is a whole-body suit and one-man life raft that was first produced in 1952. It was designed by British company RFD Beaufort Limited and allows submariners to escape from a sunken submarine. The suit also provides protection against hypothermia and has replaced the Steinke hood rescue device. The suit allows survivors to escape a disabled submarine at depths down to 600 feet (183 m), with an ascent speed of 2–3 meters/second, at a rate of eight or more sailors per hour.

An escape trunk is a small compartment on a submarine which provides a means for crew to escape from a downed submarine; it operates on a principle similar to an airlock, in that it allows the transfer of persons or objects between two areas of different pressure.