"Tamas Feher" wrote in message ...
Yes, they can fly in the air and underwater

There was some protoype USAF delta-wing jet in the early 50s that landed
on waterskid and then acted as a submarine down to 15 meters of water.

See: Convair XF2Y Sea Dart

If it submerged to 15 meters, I think that was most likely an accident.