I can with confidence say that I would not trust a dive computer that is rated to a maximum of 40 meters. It would be a bit like owning a car where the breaks w

I can with confidence say that I would not trust a dive computer that is rated to a maximum of 40 meters. It would be a bit like owning a car where the breaks were rated for a maximum of 110 km/h. Sure, most of the time you might stay under that limit, but for safety equipment you do want some margins. If a person accidental loose buoyancy for a moment and end up at 41 meters, they could really end up in a terrible situation. The added stress, not being able to monitor ascent rate, and no information regarding NDL (the no decompression limit). Humans can't survive on their own under water. Visiting there require equipment designed for that purpose. They don't need to be expensive but they do need to do the job. A 90% functional diving equipment can easily result in 100% dead diver.