Dive Watch (Diver)
A dive watch has at least 100 (ideally 200) metres of water resistance, a screw-down crown, a unidirectional rotating bezel and strong lume. Professional-grade models meet the ISO 6425 standard and carry a diver's mark on the dial.
Four things define a true dive watch: sufficient water resistance, a screw-down crown that seals out water, a unidirectional bezel that can only shorten the timed dive if it is knocked, never extend it, and strong lume you can read in the dark. The ISO 6425 standard adds tests for pressure, magnetism and shock. The word diver on a dial is not enough by itself; check the rating and the screw-down crown. The Orient Mako and Seiko Prospex are affordable yet genuine divers.