How to Choose a Dive Computer for Cairns and the Great Barrier Reef
Choosing a dive computer isn't something you want to rush. It's the one piece of gear that tracks your depth, time, decompression status, and gas supply in real time. Get the right one and it becomes the most useful thing on your wrist. Get the wrong one and you'll be squinting at a confusing screen 20 metres down on the outer reef.
We've been selling and using dive computers at our Cairns dive store for over 25 years. We know which ones hold up in tropical conditions, which interfaces actually make sense underwater, and which features matter for the kind of diving you do around the Great Barrier Reef.
What does a dive computer actually do?
A dive computer continuously monitors your depth and bottom time, then calculates your no-decompression limit (NDL) in real time. That means it tells you how long you can safely stay at your current depth before you'd need to make decompression stops on the way up.
Older divers used printed dive tables to plan this beforehand. Dive computers replaced tables because they recalculate constantly as you move between depths, giving you more accurate and usually more generous limits. They also track your surface interval between dives and adjust your limits for repetitive dives throughout the day.
For a full breakdown of dive terminology, have a look at our diving and spearfishing glossary.
What to look for when buying a dive computer in Cairns
Not all dive computers suit all divers. Here's what to think about before spending your money.
What type of diving do you do?
If you're doing recreational scuba on the GBR with a local operator, a basic wrist-mount computer with air integration will cover you. If you're doing nitrox, freediving, or multiple dives per day on a liveaboard, you'll want something with gas switching and a freediving mode. Spearfishing and freediving use different algorithms to scuba, so check that the computer supports your specific activity.
Display readability
This matters more than people think. On the outer reef at 25 metres with reduced visibility, you need to read your computer quickly. Colour screens are easier to scan than monochrome. Bigger displays help if your eyesight isn't what it used to be. Backlit screens are essential for night diving and coral spawning trips.
Battery life
Rechargeable computers are convenient but need charging between trips. User-replaceable battery computers (like the Suunto Zoop Novo) use standard CR2450 batteries that last 12 months or more. In Cairns, where you might be doing back-to-back dive days, battery reliability matters. You don't want your computer dying mid-trip on the Ribbon Reefs.
Compass and GPS
Built-in compasses are handy for navigation on low-visibility dives or when you're exploring new reef sites. GPS features (like the Garmin Descent range) can log your entry and exit points, which is useful for boat diving on the outer GBR where you're not always dropping onto the same mooring.
Dive computers we stock
We carry Garmin, Suunto, and Mares at our Westcourt store. Here's a straightforward look at what's in the range and who each one suits.
Entry level: Mares Instrument Mission 1 — $194.99
This is a solid starting point if you're new to diving or want a no-fuss backup computer. It covers air and nitrox (up to 99% O2), has a clear segmented display, and handles the basics without overcomplicating things. The Mission 1 is one of the most affordable computers from a reputable brand. If you're doing your Open Water course or taking occasional reef dives, this does the job.
What it doesn't have: no freediving mode, no colour screen, no wireless air integration. It's a straightforward scuba computer at a fair price.
Mid-range: Suunto Zoop Novo — $399.99
The Zoop Novo is probably the most popular computer we sell. It supports air, nitrox, gauge, and freediving modes, which makes it versatile enough for most FNQ divers. The display is large and easy to read. Battery is a user-replaceable CR2450, so you won't be hunting for a charger. It's got a solid reputation for reliability and Suunto's algorithms are well-proven.
Good for recreational divers who want one computer that handles scuba and freediving without spending over $500.
Mid-range: Suunto D4f — $499.99
The D4f is Suunto's dedicated freediving computer. If you're primarily freediving or spearfishing, this is purpose-built for that. It tracks depth, dive time, surface intervals, and includes a freedive-specific algorithm. The watch-style design means you can wear it day-to-day as well. It doesn't support scuba mode, so it's not a do-everything option — it's for freedivers who want a tool designed specifically for their sport.
Premium: Garmin Descent G2 — $1,079.99
The G2 bridges the gap between dive computer and smartwatch. It supports multiple dive modes (single gas, multi-gas, gauge, apnea, CCR), has a colour display, built-in GPS for surface logging, and works as a full fitness watch on land. Garmin's interface takes some getting used to if you're coming from Suunto, but once you learn it, the feature set is hard to beat.
We see a lot of Cairns locals pick the G2 because they want one device for diving and daily wear. The GPS surface tracking is genuinely useful for boat diving on the GBR.
High-end: Garmin Descent Mk3 — from $1,799.99
The Mk3 is Garmin's current flagship. The 43mm model ($1,799.99) has a bright AMOLED display and runs the full Garmin ecosystem — maps, music, contactless payments, plus all the dive features from the G2. The Mk3i 51mm ($2,498.99) adds a larger screen and SubWave sonar air integration, so you can monitor your tank pressure wirelessly.
These are serious computers for serious divers. If you're doing technical diving, regular liveaboards, or you just want the best available, the Mk3 range is where Garmin has put everything they've learned. The AMOLED screen makes a real difference underwater — it's the easiest display to read at depth that we've used.
Which dive computer for which diver?
| If you're... | Consider | Price |
|---|---|---|
| New to scuba, doing Open Water | Mares Mission 1 | $194.99 |
| Recreational diver, scuba + some freediving | Suunto Zoop Novo | $399.99 |
| Primarily freediving or spearfishing | Suunto D4f | $499.99 |
| Regular diver, want a daily smartwatch too | Garmin Descent G2 | $1,079.99 |
| Serious/technical diver, best available | Garmin Descent Mk3/Mk3i | From $1,799.99 |
Dive computer features that matter on the GBR
Some features are more relevant in Far North Queensland than they'd be in cooler or calmer waters.
Freediving mode
A lot of Cairns divers do both scuba and freediving. If that's you, get a computer that handles both. The Zoop Novo does this. The Garmin G2 and Mk3 do it well. The Mission 1 doesn't have a freediving mode, and the D4f doesn't have scuba mode. Think about what you'll actually be doing in 12 months, not just this weekend.
Nitrox support
Most GBR operators offer nitrox (enriched air). If you're nitrox certified, make sure your computer supports it and can handle the O2 percentage you'll be breathing. All the computers we stock support nitrox, but the configurable range varies. The Garmin range supports multi-gas switching, which matters if you're using different mixes on a single dive.
Water temperature logging
Cairns water temps range from about 23°C in winter to 29°C in summer. Temperature logging helps you track conditions across seasons and plan your wetsuit choices for different times of year. Most modern computers include this.
Audible and visual alarms
Ascent rate alarms are important for any diver, but they matter more when you're distracted by a manta ray or a coral spawning event. A computer that vibrates on your wrist is harder to miss than one that only beeps.
Looking after your dive computer in tropical conditions
Cairns humidity and salt water are tough on electronics. A few habits will extend the life of your computer.
- Rinse in fresh water after every dive. Don't just dunk it — run water through the sensor ports and buttons.
- Don't leave it in direct sun on the boat deck. The UV and heat up here are no joke.
- Store it in a cool, dry place between trips. A gear bag in the back of a hot car isn't ideal.
- Check the battery before each trip. If it's user-replaceable, keep a spare in your dive bag.
- For rechargeable models, charge the night before and bring your cable on liveaboard trips.
If something goes wrong, bring it into our Westcourt store. We can help with basic troubleshooting, battery replacements, and warranty claims.
Australian standards and safety
Dive computers sold in Australia should meet the relevant requirements under Australian Consumer Law for safety and fitness for purpose. All the brands we stock — Garmin, Suunto, and Mares — are established manufacturers with proper Australian distribution and warranty support.
For safe diving practices more broadly, WorkSafe Queensland's Diving Work Code of Practice covers equipment requirements for commercial diving. While recreational diving is self-regulated in Australia, the general principle applies: use well-maintained equipment from reputable brands, and replace gear that's reached end of life.
For an introduction to safe diving principles, see our guides on the 120 rule in diving and the rule of thirds for air management.
Try before you buy
A dive computer is something you want to hold, press the buttons on, and see the screen of before you commit. Photos on a website don't tell you how the interface feels or whether you can read the display without your reading glasses.
Pop into our store at Shop 1/310 Mulgrave Road, Westcourt and we'll walk you through the options. We can show you how each computer looks on your wrist, run through the menu systems, and help you figure out which one fits your diving style and budget.
Found a price online that's lower than ours? Let us know and we'll see what we can do.
Ocean Universal — formerly Spearfishing Superstore. Built for Divers, BY DIVERS.
Phone: (07) 4036 2080
Hours: Mon-Fri 9am-5pm, Sat 9am-3pm
Follow us on Instagram @ocean_universal_ and Facebook for gear updates, dive conditions, and what's happening on the reef.
Related pages
- Shop dive computers
- Diving and spearfishing glossary
- Dive store Cairns
- Dive store Westcourt
- Coral spawning Great Barrier Reef
- Minke whale season Cairns
- The 120 rule in diving
- Rule of thirds in diving
- Spearguns
- Wetsuits
- Masks
Frequently asked questions
What's the best dive computer for beginners?
The Mares Mission 1 ($194.99) or Suunto Zoop Novo ($399.99) are both good starting points. The Mission 1 is the more affordable option for scuba-only divers. The Zoop Novo costs more but adds freediving mode and a larger display, which gives you more flexibility as your diving develops.
Do I need a dive computer for the Great Barrier Reef?
Most dive operators provide basic rental computers, but owning your own means you're familiar with the interface, you trust the device, and you have your full dive history logged. If you're doing more than a couple of dives a year, your own computer is worth the investment.
Can I use a Garmin Descent as a regular smartwatch?
Yes. The Garmin Descent G2, Mk3, and Mk3i all function as full smartwatches with fitness tracking, GPS mapping, notifications, and contactless payments. Many of our customers wear them daily and only switch to dive mode when they're in the water.
What's the difference between a freediving and scuba dive computer?
Scuba computers track no-decompression limits based on breathing compressed gas at depth. Freediving computers track breath-hold dives with different safety calculations — they monitor surface intervals, depth, and dive times without the gas-related calculations. Some computers (like the Zoop Novo and Garmin Descent range) handle both modes. The Suunto D4f is freediving only.
How often should I replace my dive computer?
Most modern dive computers last 5-10 years with proper care. Replace the battery according to manufacturer guidelines (annually for user-replaceable types). If the screen becomes hard to read, buttons stop responding, or the manufacturer ends software support, it's time for an upgrade. Bring yours into our Westcourt store and we'll give you an honest assessment.
Do you service dive computers?
We handle battery replacements for user-serviceable models and can assist with warranty claims for Garmin, Suunto, and Mares. For more complex repairs, we work with the Australian distributors to get your computer sorted. Call us on (07) 4036 2080 or visit the shop.