Supercavitation which allows objects to move at extreme speeds through fluids by building a bubble of gas around themselves. In the case of Aquaman the gas would be steam caused by friction with the water. There are various naval torpedo systems in use that take advantage of this effect and scientists are theorising that a missile could achieve supersonic speed underwater. Of course something moving at that speed would be utterly devastating to anything anywhere near its flightpath...but never mind about that.
Aquaman is a character who really would have benefitted from being written and drawn by Jack Kirby.