Escape trunk

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.

Most submarines do not have the built-in eyes and rely on the DSRV establishing a watertight seal on the area surrounding the hatch.

Once the sub has settled on the correct location the skirt is pumped out and the hydrostatic pressure on the exterior of the skirt is enough to maintain the seal when the hatches are opened and the transfer undertaken.

The crew can then quickly equalize the pressure in the small chamber between the DSRV and the submarine and open their own lower hatch.

On the outside of the upper hatch of the escape trunk is often a shaft connected to the wheel that operates the locking mechanism.