opening of the well 7 the drawing also shows that the end 34 a of the retaining strap 34 is no longer attached to the support cage 30 the other end 34 c of the strap 34 remains attached to the support cage 30 though it will be appreciated that in other embodiments both ends 34 a 34 c may be detached from the support cage 30 thus mere activation of the handle 175 to operate latches 72 and disconnect the retaining strap 34 from the support cage 30 is sufficient to launch the buoyant pressure vessel 4 from the well 7 toward the water surface 21 the arrangement of the tether 8 between the submarine 1 and the pressure vessel 4 the tether 9 between the pressure vessel 4 and the life raft 5 and the tether drum 81 and brake 83 is much the same as for the first embodiment however the tether 8 passes through a port 33 formed in the bottom 32 of the support cage 30 as well as through a port 82 formed in the bottom of the well 7 as the pressure vessel 4 ascends towards the water surface 21 the tether drum 81 rotates and the tether 8 unwinds from the tether drum 81 the tether 8 is sufficiently long that the pressure vessel 4 is able to reach the water surface 21 from the maximum diving depth of the submarine 1 as the pressure vessel.