Buying a Used Dive Computer: 7 Things to Check Before You Buy

A dive computer is one of the most useful pieces of equipment a diver can own. It tracks important information like depth, dive time, and no-decompression limits, helping you plan and monitor your dives.

Buying a used dive computer can be a great way to save money, especially when you're building your first set of scuba equipment. But unlike a mask or pair of fins, a dive computer contains electronics, sensors, and software that deserve a closer look.

Here are seven things to check before purchasing one.

1. Check the screen and housing

Start with the obvious: physical condition.

Minor cosmetic scratches are common on used dive computers, but inspect the display carefully. Deep scratches, cracked glass, damaged buttons, or corrosion around the battery compartment can be signs of more serious problems.

A computer that looks good externally isn't automatically functioning correctly, but visible damage can help you identify potential issues early.

2. Check the battery

Some dive computers use user-replaceable batteries, while others require manufacturer service or have rechargeable batteries.

Before buying, find out which system the computer uses.

For models with replaceable batteries, ask when the battery was last changed and whether the compartment and seal are in good condition. A fresh battery is a plus, but it doesn't prove the computer is watertight.

For rechargeable models, check that the device charges normally and holds a charge.

3. Confirm that the buttons and menus work

Navigate through the computer's settings and confirm that its buttons respond consistently.

Depending on the model, check whether you can access dive modes, gas settings, alarms, and the logbook.

A functioning display is only part of the equation. You want a computer that can be operated reliably.

4. Research the model's age and support

Older dive computers aren't necessarily bad computers. Some straightforward models remain popular because they're easy to use and provide the essential information recreational divers need.

However, before purchasing an older model, investigate whether batteries, replacement parts, manuals, and manufacturer support are still available.

Also consider whether its features match your diving plans. A basic air-and-nitrox computer might be perfectly suitable for recreational diving, while more advanced diving may require additional capabilities.

5. Understand the difference between a function check and a pressure test

This is particularly important when shopping for used dive computers.

A computer that powers on and responds to button presses has passed a basic function check. That does not necessarily mean its depth sensor is accurate or that its housing will remain watertight underwater.

Proper pressure testing and sensor verification require suitable equipment and procedures.

When evaluating a listing, look for specific descriptions of what was tested rather than relying solely on phrases like "works perfectly."

6. Check the dive history and settings

If the computer has a logbook, review its recorded dives when possible. The logbook may provide useful context about previous use.

For your own use, make sure you understand how the computer handles previous dive information, tissue loading, and surface intervals. Clearing a logbook or resetting user preferences does not necessarily clear decompression calculations.

Always follow the manufacturer's instructions before using a secondhand computer, particularly if it has been used recently.

7. Compare the used price against a new model

A used dive computer should offer meaningful value compared with buying new.

Consider the computer's age, cosmetic condition, battery status, included accessories, available manufacturer support, and any additional testing or service it may need.

Sometimes a well-maintained used computer is an excellent purchase. Other times, a newer model with a warranty may be worth the additional expense.

The goal isn't simply to find the cheapest computer. It's to find one that fits your diving needs and budget.

Final thoughts

A quality dive computer doesn't have to be brand new to be useful. Taking the time to research the model, inspect its condition, and understand what has actually been tested can help you make a more informed purchase.

At ScubaResale, we believe clear equipment descriptions and transparent condition reporting help divers shop with greater confidence.

Whether you're buying your first computer or looking for a backup, knowing what to check is an important part of choosing used scuba equipment.