Peregrine

Shearwater built its reputation on technical computers, then took the same decompression engine, Buhlmann ZHL-16C with gradient factors, put it behind two buttons and a big color screen, and called it the Peregrine. Nothing about the algorithm was dumbed down for recreational divers. What was removed is the trimix and the closed-circuit plumbing, which leaves air, nitrox and three-gas nitrox, plus gauge mode.

The screen is the reason people switch. At 5.59 cm (2.2 in) it is roughly the size of a credit card standing on end, and it is a full color LCD rather than a segment display, so depth and no-decompression time are numerals you read rather than shapes you decode. On a 6 am dive at Shaab El Erg, with the sun not yet over the reef and a mask starting to fog, that difference is not a luxury.

One detail worth knowing before you buy: Shearwater computers never lock you out. Blow a ceiling, skip a stop, do something you should not have, and it keeps calculating and keeps showing you the numbers. Several other brands will refuse to run for 24 hours and hand you a gauge. Shearwater's position is that a diver in trouble needs data, not punishment, and it is hard to argue with.

The battery is internal and rechargeable, about 30 hours per charge at medium brightness, on a wireless USB-C cradle. Factory replaceable rather than user replaceable, which is the one thing traditionalists dislike about it. In practice 30 hours is a full week of four-dive days with the charger left in the cabin.