A dive watch is a timepiece designed to withstand underwater pressure, featuring water resistance, a unidirectional rotating bezel, and luminous markers for visibility in low-light conditions.
Dive watches must meet ISO 6425 standards: minimum 100m water resistance (though 200m+ is standard), unidirectional rotating bezel for tracking dive time, luminous markers visible at 25cm in darkness, and clear time-running indication. They're built for underwater use with enhanced sealing and shock resistance.
Unidirectional (counter-clockwise only) bezels prevent accidental rotation that could extend your calculated dive time. If bumped, the bezel only moves to show less time remaining, providing a safety margin. Moving clockwise could indicate more air remaining than actual, creating a dangerous situation underwater.
Yes, 100m (10 ATM) is suitable for swimming and snorkeling. However, serious diving requires 200m+ (20 ATM) rating. The rating indicates static pressure resistance; dynamic pressure from swimming strokes and water impact temporarily exceeds stated depth, so higher ratings provide safety margins for active use.