Abstract: Employee #1, a diver, was aiding in the placement and driving of anchor piles for an oil containment boom in 140 ft of water. Employee #1 was surface-supplied with voice communication and a video camera mounted on his helmet. Employee #1 had confirmed the position of the anchor piling on the bottom and that it was clear to drive the piling with the vibratory hammer. Employee #1 had moved clear of the piling and gave to order to start the hammer and come down on the line to drive the pile. Immediately after the hammer started and before the crane operator could start lowering Employee #1 called "All Stop All Stop" and screamed. Video from his helmet camera was lost and the voice communication either went to the sound of free flowing air or static and there was no further communication from the diver. The piling had separated from the hammer and struck Employee #1. It also fell on top of Employee #1 pinning him in the mud of the bottom. Employee #1 was killed.