Having received technical training, we always ensured we carried redundant equipment in case of failure of the primary device. A loss of the primary light in a cavern, sinkhole or cave was not a life-threatening issue when you switched to your back-up device.

Likewise, we carried redundant gas and regulators in various configurations in case of failure in an overhead or virtual overhead environment, you can’t always head straight to the surface. Needless to say, a redundant depth and bottom timer was required for obvious reasons. Even when diving recreational scuba, I carry multiple dive computers. This is especially important on overseas dive holidays where the option of fully desaturating is not possible to take possession of a clean dive computer during a trip.

Dive computers can and do fail, I have had a number of computer failures diving and would have been in real strife to effectively execute my decompression obligation otherwise. A two-week dive trip could be ruined by a dive computer failure; dive computers are not as reliable as one would think. So while some look at me strangely with two dive computers strapped to my wrist, as a former dive guide I have seen too many computer failures underwater to risk my overseas holiday for. I have a number of dive computers to choose from, why not have a redundant unit on holiday?