With its IPX7 rating the Apple Watch should be able to survive a splash or two, but it's supposedly far from fully waterproof (opens in new tab). The manual specifically warns against submerging it for long periods, swimming with it or exposing it to high-velocity water.
So of course that's exactly what someone did. DC Rainmaker put it through three gruelling tests, pushing it well beyond the limits set out by Apple.
First he took it for a 1,200 metre swim, which it survived. The heart rate measurements were inaccurate while it was submerged but everything seemingly worked fine once he got back to dry land.
Then he put it through two 5 metre dives and a 10 metre one and the watch came out of all three apparently unscathed.
Finally he put it in a waterproofing test chamber. The Apple Watch is only rated for submersion of up to 1 metre, but DC Rainmaker simulated a depth of 40 metres in the test and yet again it came out working fine.
So it seems the Apple Watch might be quite a bit more waterproof than Apple let on. Either that or he got away very lucky indeed.
Of course there's no guarantee that its watery adventures won't cause problems to develop over time, and if anything does go wrong it may not be repairable under warranty, so we'd still advise keeping yours as dry as possible.
But if you do find yourself submerged with an Apple Watch on your wrist it seems it's got a good chance of survival.