Dive computer specifications, A to Z

This index covers 50 dive computers from 9 brands, spanning roughly $200 to $1,400. Of those, 32 support wireless tank pressure in some form, 15 support trimix and 13 support closed circuit rebreathers. A dive computer is the single most important instrument a diver owns personally, which is why it gets a specification page of its own rather than a line in a roundup.

How should you read this index?

Four fields decide almost every purchase, and the rest are detail.

• Decompression model. Buhlmann ZHL-16C with gradient factors is the most transparent option, because conservatism is a setting you can see. RGBM implementations tend to be more conservative at defaults. Pelagic DSAT sits at the liberal end. Two computers on the same dive can legitimately disagree by tens of minutes, and a buddy pair runs the dive on the more conservative one.
• Display. Legibility beats size. A colour screen separates warnings from data by hue and holds up in deep blue-green light. A segment display shows fewer things, very large, and runs for a year on one cell.
• Air integration. A convenience rather than a requirement. It adds a transmitter, several hundred dollars, and an ecosystem lock, since transmitters do not cross brands. A mechanical pressure gauge stays in the kit either way.
• Battery. User replaceable means a dead cell on a trip is a ten minute fix and a hatch you have to close correctly. Rechargeable means no hatch to flood and a charger to remember.

Nothing on this page is a ranking. The cheapest unit indexed here, the Cressi Donatello at under $250, is a perfectly good first computer, and the most expensive is more computer than any recreational profile requires.