My close friend, JB, told me a story years ago, when he was a commercial diver on the Gulf Coast. There was a Jack Up drilling rig being moved when a storm came up and sunk the rig. After the storm, He was tasked to search for the bodies of the unaccounted for crewmen. He said it was zero visability and he was searching by feel. He about came out of his skin, when a survivor grabbed his leg. He was able to rescue several crewmen, who were surviving in an air pocket.