Depth charge
A depth charge was a type of underwater weapon, used against submerged vessels like submarines. 

In 2375, during Tom Paris's attempt to destroy Monean oxygen refineries on The Waters, Chakotay suggest something like a depth charge to stop him. Tuvok then modified a photon torpedo to function as a depth charge and detonate once in proximity to the . ()

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de:Wasserbombe
Explosive weapons