Board Thread:General Discussion/@comment-111.68.32.71-20131007122233/@comment-209421-20140413074240

For underwater combat, the only other equipment you have other than a gas-propelled weapon would be energy or directed-particle weaponry. Lasers, for the most part, fit that bill, and would work both above and below water. Other than those options, you're kind of limited, and energy weaponry still needs an energy source.