A newbie diver on a drift dive in Cozumel went in with a broken depth gauge. She then proceeded to start following a sea turtle, not paying attention do depth. I, also a newbie, chased her down into the current and caught her at ~115ft. And proceeded to pull her back up to the group @ around 60ft. This of course was well beyond my certification as OW, but I was her buddy and she happened to be my wife. We had a "discussion" about paying attention to the group and not getting caught up following sea life. And about checking equipment. The gauge was not functioning at all, however, she should have noticed right away (which I suspect she did) and stopped rather than going along relying on staying with the group.