Log your underwater activity with Apple Watch Ultra
The Depth app 
on Apple Watch Ultra can create summaries of your underwater activities, right on Apple Watch Ultra. Summaries are then available in the Fitness app on your iPhone.
What counts as a dive?
Apple Watch Ultra can log almost any underwater activity—swimming below the surface at the local pool, diving down to explore a reef while snorkeling, or going on a scuba adventure. Apple Watch Ultra tracks your dive under these conditions:
You use the Depth app or a third-party app that supports underwater activity tracking.
Your depth exceeds 1 meter and you’re submerged for more than 5 seconds.
A logged dive can be a single dive, such as a scuba dive, or a series of dives that are aggregated together—for example, when you’ve submerged multiple times to work on your breath control at the pool.
Ending a dive
Your Apple Watch Ultra starts tracking your dive after you’ve exceeded the minimum depth and time. Dives end under the following conditions:
Dives of less than 3 minutes: The dive ends when you come to the surface and press and hold the Digital Crown to turn off Water Lock, or your Apple Watch Ultra has been out of the water for 10 minutes.
Dives of more than 3 minutes: The dive ends when you come to the surface and press the Action button, turn off Water Lock, or have been out of the water for 10 minutes.
If you descend again within 10 minutes without pressing the Action button, your time underwater is added to the previous time you were submerged and is logged as a single dive.
View the dive history on your Apple Watch Ultra
Open the Depth app
on your Apple Watch Ultra.Tap View Recent Dives.
Recent dives appear, showing the date and time the dive started, the dive’s maximum depth, and the amount of time underwater.
To see more details, tap a dive.
View dive details in the Fitness app on iPhone
A dive summary is stored on Apple Watch Ultra for seven days before being automatically deleted. It’s also stored in the Fitness app on iPhone, where it remains unless you choose to delete it by swiping left on the dive, then tapping Delete.
To view all of your dive summaries, follow these steps:
Open the Fitness app on your iPhone.
In the Summary tab, tap Show More next to History.
Tap a dive to see such details as maximum depth, underwater time, water temperature, and more.
Note: The Fitness app stores dive summaries created by the Depth app as well as those created by third-party apps that support underwater activity tracking.