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.
View inside a submarine escape trunk, looking up from below the lower hatch
An airlock is a compartment which permits passage between environments of differing atmospheric pressure or composition while minimizing the mixing of environments or change in pressure in the adjoining spaces. "Airlock" is sometimes written as air-lock or air lock, or abbreviated to just lock.
An airlock on board the Space Shuttle.
US Navy submarine diving lock out, 2007.
STS-103 closing the airlock