In order to effect an escape from the stricken vessel, the escaping crew were required to enter the submarine’s only escape chamber, which could only accommodate one person at a time. As the pressure outside the submarine was greater than the pressure inside, this had to be equalised before the outer door of the escape chamber was opened. The escape chamber was flooded with the occupant having to wait until the chamber was completely full of water. Only then would the pressure within the escape chamber be equal to the outside sea pressure.