Garmin is rolling out a fresh software update for its Descent Mk3 and Descent Mk3i watch-style dive computers, bringing new diving tools and meaningful refinements for serious divers. The latest release, System Software 25.21, is the second stable update for these wearables in 2026, following the earlier 25.14 version that focused largely on squashing bugs.
One of the biggest additions in System Software 25.21 is Dive Setup Sharing for both the Descent Mk3 and Descent Mk3i. This new feature makes it easier to keep multiple Garmin dive devices aligned by letting you copy key dive setup details—such as your gas list and conservatism settings—to another compatible Garmin device. If you use more than one unit or dive with a partner who wants to mirror a proven configuration, this can save time and reduce the chance of setup mistakes before getting in the water.
Garmin is also improving the way Gradient Factor 99% (GF99) information is presented when you’re back at the surface. For divers who rely on decompression tracking and want clearer post-dive data, this adjustment should make surface checks more useful and easier to interpret.
Descent Mk3i owners are getting several extras that focus on advanced configurations and reliability. The update adds Sidemount support, including alerts that notify you when there’s a pressure difference between two linked tanks—an especially helpful safeguard for divers managing dual cylinders. The Mk3i also gains a new Redundant Time Remaining (RTR) data field, giving divers another way to monitor remaining breathing time with redundancy in mind.
Accessory performance gets attention here as well, with enhanced connection stability for linked Descent S1 buoy accessories on the Mk3i. And for those who track details closely after each dive, Garmin has included a fix for a logging issue that could cause the dive log to display incorrect final tank pressure values.
System Software 25.21 is available now for all Descent Mk3 and Descent Mk3i users. You can install the update using the Garmin Dive app, the Garmin Connect app, or Garmin Express.
