Garmin Descent Mk3i: Australian Diver Review

The Garmin Descent Mk3i is the dive computer to buy if you want one device that runs your dives, your training, your sleep tracking, your runs and your work calendar, and you can stretch the AU$2,400 price point. It is the smartwatch-shaped flagship of the Descent line, replaces the Mk2S as Garmin's top dive computer for 2026, and adds the features the Mk2S quietly lacked: an AMOLED display, air integration via the Descent T2 transmitter, and SubWave sonar-based buddy messaging. The question this review answers is whether existing Descent G1 and Mk2S owners should upgrade, and whether a new buyer should reach past a Shearwater Teric for the Garmin.

## Overview: Garmin Descent Mk3i

The Mk3i comes in two case sizes, 43mm and 51mm, both with sapphire crystals, both rated to 200 metres, both running the AMOLED panel Garmin first shipped on the Epix 2 smartwatch. The visual difference between the Mk3i and any prior Descent is immediate. Where the Mk2S used a transflective MIP screen that needed sunlight or backlight to read, the Mk3i drives a bright colour display that stays legible at 30 metres in turbid Sydney water without manual brightness adjustment. Battery life takes the inevitable hit, 66 hours in dive mode and around 25 days in smartwatch mode, but those numbers still beat every direct competitor.

For Australian divers, the Mk3i sits in the upper bracket of the market against the Shearwater Teric (around AU$1,800) and the Garmin Descent Mk3 (no air integration, around AU$1,799). The Mk3i premium over the Mk3 buys air integration plus SubWave; the Mk3i premium over a Teric buys the smartwatch layer, AMOLED, GPS dive logging and Garmin's broader fitness ecosystem. Whether that is worth the gap depends on whether you actually wear the watch between dives or strap it on for the morning brief and stow it in the BCD pocket on the boat ride home.

## Key Features

- 1.4-inch AMOLED colour display, sapphire crystal lens, leakproof metal inductive buttons - 43mm and 51mm case sizes, titanium or DLC titanium construction - 200 metre dive depth rating, IP68 surface rating - Bühlmann ZHL-16C algorithm with user-adjustable gradient factors - Single-gas and multi-gas nitrox, trimix, CCR, gauge and apnea dive modes - Air integration with up to five Descent T2 transmitters (sold separately, around AU$500 each) - SubWave sonar diver-to-diver messaging, up to eight connected buddies, preset SOS message - GPS dive entry and exit logging, on-watch colour maps for dive sites - Built-in white LED flashlight on the case side - 66 hour dive battery (smartwatch use: 25 days), USB-C charging - Garmin Connect sync, Shearwater-Cloud equivalent dive log app integration - Over 100 sports activity profiles, full fitness tracking, smartphone notifications

## The Good

- **The AMOLED display is the headline upgrade.** Reading depth and NDL at 28 metres in green water with the Mk2S meant tipping the wrist to catch ambient light. The Mk3i is just bright. The 320-nit baseline holds up under direct tropical sun and reads cleanly in low-viz Port Phillip on the same dive trip. - **SubWave is the first practical dive-buddy comms in a recreational price bracket.** Eight-buddy linking with preset messages including a help flag actually changes how you can run a pair or trio on a Yongala drift. It is not a replacement for a tow-float or surface marker, but it is the first time the safety story moved forward in years. - **Air integration is now standard.** The Mk2S required the Mk2i for AI. With the Mk3i, the Descent T2 transmitter pairs out of the box; one transmitter per buddy if you want to monitor each other's gas, up to five. - **The smartwatch case is the deciding factor for travel.** A Mk3i that lives on your wrist between dives is one less item to pack, one less device to charge in a [Coral Bay](https://scubadownunder.com/dive-sites/coral-bay) caravan park. The Teric does the same trick at a smaller price, but with a smaller fitness/maps story. - **Garmin's firmware update cadence has improved.** Mk2S owners watched feature parity slowly arrive over three years. The Mk3i shipped feature-complete and has received four firmware updates in the first six months of release.

## The Bad

- **AU$2,400-2,800 is a serious cheque.** For the same money you can buy a Shearwater Teric plus a Perdix 2, or a [Suunto D5](https://scubadownunder.com/gear-reviews/suunto-d5-dive-computer) plus a [Cressi Leonardo](https://scubadownunder.com/gear-reviews/cressi-leonardo-underwater-diving-computer) plus a year of liveaboards. Cross-shop the Teric specifically before committing. - **The smartwatch layer is the value driver, but only if you use it.** If you wear a separate Garmin Forerunner or Fenix already, the Mk3i duplicates that hardware. If you don't run, lift or cycle, half the Mk3i story is dead weight. - **The Descent T2 transmitters are an additional spend.** AU$500 per transmitter, which means a four-cylinder tech rig adds roughly AU$2,000 to the base Mk3i purchase. Plan the total cost up front. - **SubWave currently has a thin global install base.** Useful when both buddies have one, ornamental when they don't. The feature gets stronger as Mk3i adoption spreads.

## Verdict

The Garmin Descent Mk3i is the right dive computer for the diver who already lives in the Garmin ecosystem and dives twenty-plus times a year. The AMOLED screen, SubWave comms, GPS dive logging and built-in air integration land the Mk3i in clear lead among recreational-bracket flagship computers, and the upgrade from a Mk2S is genuinely meaningful for anyone using the smartwatch features off the boat. Mk2S owners not interested in air integration or the smartwatch story should stay put. [Garmin Descent G1](https://scubadownunder.com/gear-reviews/garmin-descent-g1-dive-watch) owners should think hard about whether they need the upgrade or whether the G1 plus a [Suunto Zoop Novo](https://scubadownunder.com/gear-reviews/suunto-zoop-novo-wrist-scuba-diving-computer) as backup is the better split of the same budget. New buyers cross-shopping should price a Shearwater Teric in the same purchase decision before committing.

Star Rating: ⭐⭐⭐⭐½ (4.5/5)