What do you know about supercavitation transport?

Answer 1

If you've got a submarine shaped like a flat-nosed bullet and accelerate it to supercavitation speed, a few hundred km/hour, the water in front of it will be pushed sideways and the sub will be surrounded by a bubble containing nothing but a little water vapour at low pressure. The only part of the sub in contact with the water would be the flat nose tip. If you could make it work, you'd cross the Atlantic at airliner speed. Problems that spring to mind are the huge amount of energy you'd need, how you'd see far enough ahead to avoid an obstacle like a whale, and the effect on marine life. A possible fuel would be aluminium powder, which you'd react with the water.