Dive Watch (Diver)
A dive watch has at least 100 (preferably 200) meters of water resistance, a screw-down crown, a one-way 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: enough water resistance, a screw-down crown that seals out water, a one-way bezel that can only shorten the timed dive if 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 on its own; check the rating and the screw-down crown. The Orient Mako and Seiko Prospex are affordable yet genuine divers.