Mares Dive Computer Watch: How to Choose and Use One Safely (2026)

Updated November 2026

A mares dive computer watch combines a wrist-worn timepiece with the depth, time, and decompression tracking you need underwater. This guide walks you through choosing a model that fits your diving, setting it up correctly, and avoiding the errors that cause trouble on a dive. By the end, you will know what to check before you buy and how to use the watch with confidence.

Step 1: Match the Watch to Your Diving

Start with how you actually dive. A recreational diver who stays within no-decompression limits has different needs from someone who plans technical or deep dives. Mares offers watch-style computers across a range of features, so compare the ones that fit your certification level and dive profile. If you are still deciding between a wrist computer and a console-mounted unit, the guide on Wrist Watch Dive Computer: How to Choose and Use One Safely (2026) explains the tradeoffs.

Shopping for one? See our guide: Dive Computer vs Dive Watch (2026): Which Is Better for Women Divers?.

Step 2: Check Fit and Wrist Size

Women often have smaller wrists, and a bulky case can slide or pinch under a wetsuit sleeve. Measure your wrist circumference just above the wrist bone. Then look at the case diameter and strap length. A watch that sits too high on the arm can catch on gear, while one that is too loose can shift during a dive and make the screen hard to read. The article on Watch Size Dive Computer (2026): Which Should You Choose? covers sizing in more detail.

Step 3: Set Up the Watch Before Every Dive

Most dive-related errors come from setup mistakes, not from the watch itself. Before each day of diving, confirm the following:

1. Battery or charge level is adequate for the full day of dives.
2. Units (metric or imperial) match your local habits and your buddy’s display.
3. Altitude or water-type settings are correct if you dive at elevation or in saltwater versus freshwater.
4. Your conservatism or safety settings match your training.
5. Your personal details, such as your dive log entries, are current.

The Mares user manual for your model lists the exact menu paths. Read the section on setup and use before your first dive, not on the boat.

Step 4: Read and Respond to the Display During the Dive

Check the watch at regular intervals, not only when something feels wrong. Note your depth, elapsed time, ascent rate, and any decompression or safety stop prompts. If the watch shows a warning, follow your training: slow down, stop, or begin your ascent as instructed. Never ignore an alert because you feel fine. Symptoms of decompression sickness can appear after the dive, so the computer’s data is your best record.

Watch for These Warning Signs

• Ascent rate indicator flashing or in the warning color
• Decompression ceiling or no-decompression time running low
• Safety stop countdown appearing on the display

Common Mistakes

• Diving with a low battery and assuming it will last the day.
• Mixing units between your watch and your buddy’s computer, leading to misread depths.
• Skipping the surface interval. Many computers need time to clear residual nitrogen before the next dive.
• Wearing the watch too high on the arm, where it can pull or catch on gear.
• Assuming a wrist computer replaces training. It does not.

Recommended Gear

• A soft wrist pad or strap cover helps the watch sit flat and reduces chafing under a thick wetsuit sleeve. View on Amazon
• A dive computer case or sleeve protects the screen and buttons when you transport the watch between dives. View on Amazon
• A spare charging cable keeps the watch ready between dive days when you are traveling. View on Amazon

FAQ

Can I use a Mares dive computer watch for technical diving?

Only if the model is rated for it and you hold the appropriate training. Check the manufacturer’s specifications and your certification requirements before planning any deep or decompression dive.

How often should I service my dive computer?

Follow the manufacturer’s service schedule, which is usually tied to battery replacement and seal checks. Have it inspected after any impact or water leak. Consult an authorized dealer for service.

Do I need to log my dives in the watch?

Most models store dive history automatically, and logging helps you track surface intervals and patterns over time. Keep a separate paper or app log as a backup in case of data loss.

Conclusion

Choosing a mares dive computer watch starts with your diving style and wrist size. Set it up carefully before every dive, and treat its warnings as instructions rather than suggestions. Consult a qualified dive professional whenever you are unsure how to apply the data to your dive plan.

Related reading

• Mares Nemo Wide Dive Computer Wrist Watch Manual: Setup and Use Guide
• Suunto Zoop Novo Dive Computer Wrist Watch: 4 Best Picks Compared (2026)

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