When I did a BSAC Sports Diver thingy 25 years ago we had our own 'escape' at Vivian. Back in those days, you didn't have the luxury of a set of steps down to a diving platform. It was a barrel roll, landing on your back 5 foot lower down in the water. There were three of us with an instructor; we three dived to the bottom, but one of our compadre's weight belt had become detached, possibly as a result of a glancing hit on the side that he had when he entered the water, and he was like the proverbial cork. We other two managed to reach the belt, whilst restraining our colleague from launching himself upwards like a Polaris missile. No sign of our diving instructor, so we signalled to each other that we would ascend. Which we duly did, but with one of us like a cork, and the other two down one hand each from holding onto the dive belt, control of the stab jacket was less than perfect, and we were accelerating as the air in the jacket expanded as the water pressure reduced. My fellow belt holder had the presence of mind to dump air from his jacket in order to slow our ascent, but I swear we must have cleared 5 foot when we hit the surface, with a volumable 'fucking hell' from the spectators amassed above. Then a paniced 'hold onto the belt' from my colleague who had dumped his air lest he disappear back into the murky depths. Needless to say, we called it a day, and retired to Pete's Eats, inspecting our joints for a rash which might indicate a case of the bends. But the dive had been so short lived, we were fine.