Dr. Finch in Aquanox 2, just before the "Machina Antarctica" mission, mentioned that she was making a "Sonic Laser," which at the time of the game's release I thought to mean nothing more than unsubstantiated "technobabble" (meaningless words that are supposed to sound like they're referring to something highly advanced).
Well, whether or not it was technobabble to begin with (and we can't ask Herr Halfmann about this anymore), recent advances have made an actual "Sonic Laser weapon" (stimulated emission of Phonons, the basis of sound rather than Photons which are the basis of Light or electromagnetic radiation) tantalizingly possible. Whether or not it can actually be weaponized in our lifetimes is anyone's guess at this point in time; the current outlook is that it would be used to scan things via ultrasound more effectively and at a distance (ultrasound scans right now require that you have to hold the scanner against whatever it is you're scanning).
I definitely would have liked to have seen a Sonic Laser in Aquanox 3 (though whether it would have been a measurable improvement over the Sizzler weapon is anyone's guess).