If a diver's computer fails and there is no backup, what is a reasonable course of action?

• A. End the dive and ascend slowly with a safety stop
• B. Replace the computer with a smartphone app
• C. Continue diving as planned
• D. Ignore the failure

Answer: (A)

When a dive computer fails and there’s no backup, you can’t reliably track depth, bottom time, or decompression status. The safer choice is to abort the dive and ascend in a controlled, conservative manner, performing a safety stop at a shallow depth (for example around 15 feet) for a few minutes if conditions allow. This pause gives excess nitrogen time to off-gas and reduces the risk of decompression sickness since you’re no longer relying on uncertain computer data.

Replacing the computer with a smartphone app isn’t a dependable backup in a wet environment, and continuing the dive with no working computer or ignoring the failure both expose you to greater decompression risk. Using pre-dive plans or tables without a working computer is possible in some cases, but with no backup data available in the moment, aborting the dive is the prudent choice.