Depth Charge

You can hurl a canister of hyper-compressed water that explodes in water. Each creature within a 15- foot cube must take a Constitution saving throw, on a failed save they suffer 3d8 points of bludgeoning damage and are pushed 15 ft. away from the source of the explosion, on a successful roll they take half damage and are not pushed. A depth charge deals double damage to the hulls of boats, ships, submersibles, and other water vehicles. A depth charge deals no damage to creatures or objects that are not in the water.

Rather than hurling a depth charge for immediate detonation, you may drop the depth charge into the water and allow it to sink at a rate of 30 feet per round, delaying its explosion by up to 3 rounds. A creature in the water can pick up the depth charge and move it, though there is a 25% chance each round it is handled that it detonates immediately.