The Apple Watch's "water lock" feature protects the device when it gets wet by disabling the touchscreen (so water pressure doesn't trigger accidental taps) and actively ejecting trapped water through the speaker holes to speed up drying. Although modern Apple Watches carry water-resistance ratings that make them safe for swimming, resistance weakens over time, so removing residual moisture after exposure helps prevent internal damage and prolongs the device's lifespan.

The feature has been available from the Apple Watch Series 2 onwards and can be switched on manually via the water droplet icon in Control Centre, or is triggered automatically during workouts such as swimming or surfing. Apple Watch Ultra models also support it while scuba diving, unlike standard models. To turn it off, users press and hold the Digital Crown, prompting a series of tones as water is forced out through the tiny speaker openings in repeated bursts until the watch is dry.