A launch canister for ejection from a submerged launch platform, the launch canister being adapted for ejection in a direction substantially along a first axis of the launch canister and comprising: an enclosure for carrying a UAV; a nose cap releasably located in a launch opening at a forward end of the launch canister; a launch mechanism for driving a UAV carried in the enclosure out of the launch canister through the launch opening in a direction substantially along said first axis; and a water surface sensor for detecting when the nose cap of the canister broaches the surface of the water; wherein the launch canister is configured to, on the water surface sensor detecting that the nose cap of the canister has broached the surface of the water, immediately release the nose cap and initiate the launch mechanism to drive a UAV carried in the enclosure out of the launch canister through the launch opening.