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Garmin Descent T2 Transceiver and Descent S1 Buoy: SubWave Sonar for Divers
These two products turn a Descent Mk3i or X50i into a networked dive system. The Descent T2 transceiver adds wireless air integration and diver-to-diver messaging underwater. The Descent S1 buoy connects that underwater network to the surface, so a boat crew or shore support can track divers, exchange messages and get tank-pressure alerts in real time. Both run on Garmin's SubWave sonar technology, which uses acoustic signals underwater because they travel farther than the radio signals other systems rely on.
At DiveCatalog.com we stock the T2 and the S1 as an authorized Garmin dealer, and we dive them. Specifications below come from Garmin's official product pages and owner's manuals.
Descent T2 Transceiver
| Spec | Descent T2 |
|---|---|
| What it does | Transmits tank pressure and depth to compatible Descent computers and enables preset underwater messaging |
| Tanks per computer | Up to 8 transceivers paired to each compatible air-integrated computer |
| Tank pressure range | Up to 10 m (33 ft) |
| Messaging range | Up to 30 m (98 ft), requires Mk3i or X50i |
| Surface range | Up to 10 m over ANT wireless |
| Battery | User-replaceable CR123A, up to 100 hours |
| Ratings | Dive 200 m water rating; 300 bar (4,351 psi) pressure rating; 7/16 inch 20 UNF HP port thread |
| Compatible computers | Descent Mk3i and X50i (full: send and receive messages, tank pressure, depth, distance, tank name); Descent Mk2i (receive messages, pressure, depth, distance); Descent S1 buoy |
Mounted on the high-pressure port of a first stage, the T2 sends tank pressure, depth, gas time remaining and consumption rate to every paired computer within 10 meters, so you can monitor your own cylinders, sidemount or stage bottles, and your buddies' tanks. With a Mk3i or X50i, SubWave also carries preset messages such as "Are you OK?" or "Come to me" to other T2-equipped divers up to 30 meters away. On the surface it switches to ANT. Garmin's note: the T1 is the previous generation and supports tank pressure only, not messaging; the Mk3 (non-i), G2 and X30 are not transceiver compatible.
Descent S1 Buoy
| Spec | Descent S1 |
|---|---|
| What it does | A diver communication buoy that lets topside crew track dive groups and exchange preset messages with divers below |
| Divers tracked | Up to 8, with approximate range to each |
| Underwater range | Up to 100 m (328 ft) line of sight via SubWave sonar |
| Surface connection | Wi-Fi to the Garmin Dive app on a phone, up to 60 m (197 ft) |
| Alerts | Automatic low-tank-pressure alerts topside; diver recall; divers get distance and direction back to the buoy |
| After the dive | Underwater heat maps of approximate diver locations in the Garmin Dive app |
| Battery | Internal rechargeable, up to 15 hours, USB-C clip charger |
| Size and weight | 203 x 135 mm; 2.2 lb (981 g); buoy rated IPX8 to 10 m |
| Requirements | Descent Mk3i or X50i computer plus a Descent T2 transceiver per diver; the Mk2i is not supported |
Announced July 2025, the S1 gives dive operators, instructors and expedition teams something that did not exist before: a live picture of where their divers are, how much gas they have and a way to tell them to come up. Divers see distance and direction to the buoy on their Descent, which doubles as a navigation aid back to the boat. A carrying case with drain grommets is available separately.
How a SubWave Setup Fits Together
1. Each diver wears a Descent Mk3i or X50i.
2. Each cylinder you want monitored gets a Descent T2 transceiver on the HP port, paired to the computer. Up to 8 per computer.
3. With T2s on both divers, computers exchange preset messages to 30 meters and show each other's depth and distance.
4. Add a Descent S1 buoy on the surface and the topside team tracks everyone to 100 meters through the Garmin Dive app, with tank alerts and recall.
Garmin's safety note applies to the whole system: messaging and assistance features should not be relied on as a method to receive emergency assistance and do not replace traditional dive safety tools and procedures.
Why Buy from DiveCatalog.com?
- Authorized Garmin dealer and dive shop: genuine T2 and S1 with the full Garmin warranty, sold by people who use them
- Complete systems: pair a T2 or S1 with a Descent Mk3i or X50i in one order
- Fast shipping from Irvine, California, and easy returns and exchanges
- Rewards program: earn points on every purchase
Frequently Asked Questions: Descent T2 and S1
Which Garmin computers work with the T2?
Descent Mk3i and X50i get the full feature set including sending and receiving messages. The Mk2i receives messages and tank data but cannot send. The Mk3, G2 and X30 are not compatible.
Does the T2 work with the Mk3i's messaging?
Yes. T2 transceivers are what carry SubWave messages. The older T1 does tank pressure only.
How many T2 transceivers do I need?
One per cylinder you want to monitor. A single transceiver gives you air integration; one on each buddy's tank gives you messaging and buddy tank monitoring.
Do I need a phone for the S1 buoy?
Yes. The topside crew uses the Garmin Dive app on a phone connected to the buoy over Wi-Fi within 60 meters to see divers, read tank alerts and send messages.
Is the T2 battery rechargeable?
No. It uses a user-replaceable CR123A lithium cell rated for up to 100 hours of diving.
Browse the Descent T2 and S1 above, and see the complete Garmin Dive collection for computers and accessories.