"Although neither diver had any technical-diving training, a fellow diver set them up with twin air tanks. They were planning to follow their dive computers for the decompression stops they knew they would have to make on the way back from 230 feet. Both young men had recently completed dives to 200 feet, so they saw this dive as the next step in their personal evolution. They were making the dive breathing air."
Thanks BOB for lending me your twinset, this type of enabeling behaviour really doesn't help young and enthousiastic divers, a twinset is a whole lot more than just a bigger amount of gas, it's a ticket to a deeper world, and a temptation to push boundaries, and as such shouldn't just be handed to people, unless they have enjoyed training that warrants the use of a twinset. The 2 guys had done deep air dives before, and following the classic "ow I didn't die so therefore i'm safe" mindset they pushed on.
I know when you're 18 you're invincible, and sure, these kids were stupid, and I hear you thinking "yeah but we live in enough of a nanny state, we can't put fences around everything", and you'd be right in thinking that......
BUT.....If you put fences around the little things, the little problems, then people never learn the lessons intended to stop them from doing bigger more dangerous stupid things.
So next time you teach an open water student, don't make it so bloody easy, make them plan a dive, plan their gas consumption, take their computers away and give them a timer and a set of tables. Just make them think a little, you are afterall sending them home, telling them they are now certified divers, capable of planning and diving without any supervision.