DESCENT X30

The Garmin Descent X30 puts a 2.4 inch colour screen on the wrist for divers who want the numbers large and the interface plain. Its housing and bezel are moulded from recycled ocean-bound plastic, and it runs on four leakproof metal buttons rather than a touchscreen, so it stays operable in thick gloves.

The case is dive rated to 100 metres, with chemically strengthened glass over a 320 by 240 colour display. Decompression is Buhlmann ZHL-16c with gradient factors across air, nitrox and trimix to 100 percent oxygen, in single-gas, multi-gas and gauge modes. Battery life is 30 hours at default brightness and 47 hours on a night dive. A three-axis dive compass gives quick 90 left, 90 right and reciprocal headings.

The result is a computer that answers a mid-dive question without a menu. Audible and vibration alarms cover ascent rate, oxygen partial pressure, no-decompression limit, decompression and gas switching, and the planner handles no-stop and multi-gas decompression before the diver gets wet.

The unit measures 78.7 by 61.8 by 24.7 millimetres and weighs 198.2 grams on its hinged silicone band, which adjusts from 140 to 360 millimetres over a suit. In the box: the computer and band, a charging clip and cable, a screen protector kit and documentation. The X30 has no air integration and no rebreather mode; the X50i is the air-integrated model in the same format.