https://www.cnet.com/news/we-took-the-iphone-xs-and-xr-into-26-feet-deep-extreme-water-test-one-survived/

We've already put the XS to the test in our earlier water test, and it survived being submerged in chlorinated pool water for 30 minutes. It wasn't fazed by splashes of hot tea, wine or a shallow swim in the salt water of the San Francisco Bay either.

To raise the stakes, we took a new iPhone XR and the same XS that survived our initial pool test to Monterey Bay in California. We strapped the two phones to the front of the Trident, an underwater drone from OpenROV. It can reach depths of up to 100 meters, although the bay isn't anywhere near that deep.