The present invention relates to a water activated inflator and a method of air deployment of a water activated inflatable device. A gas cylinder opening device for opening a sealing mechanism of the gas cylinder is disposed in the housing movable along a first axis having a first orientation between a cocked position and a fired position. A tension mechanism provides tension acting along the first axis for moving the gas cylinder opening device from the cocked position to the fired position. A plunger is holding the gas cylinder opening mechanism in the cocked position. The plunger is movable along a second axis having a different second orientation between a first position and a second position. A water soluble element is holding the plunger in the first position. A first interacting surface of the gas cylinder opening device is disposed at a predetermined angle to the first axis. A second interacting surface of the plunger is in contact with the first interacting surface at the predetermined angle. The angle is determined such that a component along the second axis of a component of the tension acting onto the second interacting surface is within a predetermined range for ensuring structural integrity of the water soluble element in the cocked position and for ensuring movement of the plunger when at least a portion of the water soluble element is dissolved. Using the water activated inflator in a rescue kit is highly beneficial for air rescue operations over a body of water by providing proper timing of the inflation shortly after impact.