A reliable sports watch for diving is an essential instrument for dive safety. Certain key features make for a good dive timepiece. The first thing to look for is water-resistance for at least 200 meters (660 feet) or greater. There is nothing wrong with having greater water-resistance than you actually need, and ISO certification is a plus.
Because accurate timing is crucial for safe diving, most dive timepieces come equipped with a unidirectional rotating timing bezel etched with a 60-minute scale and a special luminous marker at the 12 o’clock position for proper orientation at all times. The dive bezel rachets only counter-clockwise so that if it should get bumped accidentally, it can only turn in the direction that shortens the amount of time allotted for the dive in order to keep the diver from thinking that he has more air time underwater than he actually has to prevent running out of air at the worst possible time.
Finally, sport watches for diving will have generous illumination, with large luminous hands and hour markers for clear legibility even in murky depths. While some diver timepieces have other features such as depth meter or helium escape valve, or even computerized functions, sufficient water-resistance, unidirectional rotating timing bezel, and generous illumination are the hallmarks of a classic dive watch made for diving safety.