The Apple Watch has always been able to shrug off some amount of water, but since the Series 2 it’s been able to survive being completely submerged, accidentally or not. The only caveat is that water can get trapped in the smartwatch’s speaker, a problem Apple has solved with a clever water-eject feature that is fascinating to see in action through the lens of a high-speed camera.
In recent months, while trapped inside due to the pandemic, The Slow Mo Guys have had to come up with some clever experiments for the YouTube channel where they reveal the world’s split-second secrets that are otherwise missed by the human eye. It’s doubtful that you pay much attention to the Apple Watch’s water-eject feature when you use it, aside from drying off your arm after it finishes its series of quick chirps. But at 2,000 frames per second, you can finally see exactly how the feature works.
The chirps you hear aren’t just the Apple Watch audibly letting you know the water-eject feature has been activated. They actually cause the tiny diaphragm inside the Apple Watch’s speaker openings to move in and out, effectively turning them into a pump that forces out trapped water. The diaphragm’s in-and-out motions eventually start pulling in as much water as they push out, so they’re paused for a brief moment, allowing the liquid inside to settle before starting the vibrations again and ejecting more.
It’s why you hear a series of 10 quick chirps when the water eject feature is activated, instead of a prolonged single tone. The Slow Mo Guys clearly aren’t the first people to put the smartwatch under a macro lens; Apple’s testing team undoubtedly discovered the behavior first, which is why the water-eject feature works like it does.