An air bag launch assembly is disclosed which allows for modular loading onto a submarine, the launch of weapons or vehicles external to the submarine pressure hull, while also achieving greater packing density. The air bag launch assembly includes a large, watertight pressure container; one or more smaller, watertight canisters used to contain the weapon or vehicle. The canisters are sized to fit within the larger pressure container. An air bag inflator is attached to the top and/or sides of the small canister to buoy the canister out of the container.