The Ultimate Guide to Buying Your First Dive Computer
In the early days of scuba diving, divers relied on plastic “dive tables” and analog depth gauges to calculate how long they could safely stay underwater without risking Decompression Sickness (the bends).
Today, nobody uses tables. A dive computer tracks your depth and time dynamically, updating your safe limits every single second. After your mask and fins, a dive computer is the absolute most critical piece of gear you must buy.
Here is how to navigate the market.
1. Why You Need Your Own (Instead of Renting)
While most dive centres will rent you a computer alongside your regulator, relying on rentals is a bad idea.
- Familiarity in an Emergency: Every computer brand has a different menu system. If you hit your safety limits and an alarm starts beeping, you need to know exactly what the screen is telling you immediately. You cannot do this if you are using a different rental model on every trip.
- Tracking Multiple Dives: If you are doing a 3-day Liveaboard trip in Cairns, the computer tracks your cumulative nitrogen load over several days. You cannot swap rental computers mid-trip.
2. Form Factors: Puck vs. Watch Style
Dive computers come in two main physical styles.
The “Puck” Style (Entry Level)
These are large, robust devices about the size of an ice hockey puck. They are usually worn on the wrist with a thick rubber strap or housed in a console attached to your regulator hose.
- Pros: They are inexpensive (often under £200/$250), have massive, easy-to-read numbers, and are virtually indestructible.
- Cons: They are bulky and cannot be worn as everyday watches.
- Best for: Divers on a budget, or those who only dive once a year on holiday in places like Hurghada. Popular models include the Suunto Zoop or Mares Puck Pro.
The Watch Style (Mid to High-End)
These look like bulky sports watches (similar to a G-Shock) and can be worn to the office when you aren’t diving.
- Pros: Highly convenient, often feature brighter color screens (on high-end models), and transition seamlessly from the boat to the bar.
- Cons: The screens are smaller (tougher for older eyes), and they are significantly more expensive (£300 to £1000+).
- Best for: Frequent divers and professionals. Popular models include the Garmin Descent series or the Shearwater Teric.
3. Key Features to Look For
When shopping, ignore the marketing jargon and focus on these critical features:
- Nitrox Capability: Even if you only have your Open Water certification right now, you will eventually take the Enriched Air Nitrox specialty. Ensure the computer can be set to dive gas mixtures up to at least 40% oxygen.
- User-Replaceable Battery vs. Rechargeable: Entry-level computers use standard coin batteries (like a CR2450) that you can swap yourself with a coin. High-end modern computers use USB charging. Avoid mid-range older models that require you to send the computer away to a technician just to change the battery.
- Backlight/Screen Type: If you plan on doing Night Dives or diving in cold, dark water, a bright OLED or color LCD screen is vastly superior to a standard LCD screen with a dim backlight.
Pro Tip: Look for a computer with a “Conservative Factor” adjustment. This allows you to tell the algorithm to be stricter if you are feeling tired, dehydrated, or are diving in very cold water, adding an extra layer of safety to your dive profile.
4. What is Air Integration?
As you move into the £600+ price bracket, you will encounter “Air Integrated” (AI) computers.
Instead of looking at an analog pressure gauge attached to a hose to see how much air you have left in your tank, you screw a wireless transmitter into your regulator. This transmitter beams your tank pressure directly to your wrist computer.
- The Benefit: It puts all your critical information (Depth, Time, Safe Limits, and Air Remaining) on one single screen. It will even calculate exactly how many minutes of air you have left based on your current breathing rate!
- The Verdict: It is an incredible luxury, but absolutely not necessary for a beginner.