Underwater pipe and pile cutter - GIF

[Frank S]

Diver in the water. With the proper guards I would have welcomed one of those things. Having used an underwater cutting torch using hydrogen & oxygen with compressed air to create an air bubble to protect the flame, a sudden current could force you to move the torch at the wrong time changing the angle you were holding it moving you off your cut or worst yet cause you to lose the air bubble extinguishing the flame. You would know it immediately by the concussion of the flame making a boom as it went out. making you surface to relight it. lighting it under water was not a good option as the boom from the hydrogen oxygen and compressed air could bust your ear drums.
Another bad thing is it is almost impossible to even see the flame when burning hydrogen. At least if you were cutting at a depth of 10 feet or less you could use acetylene