To earn that distinction, a watch has to function while immersed in water for 50 hours. The watch also must have a luminous tip on the second hand, so that it can be seen even in the dark ocean depths, leeds united kit 24/25 and continue to function when exposed to salt water and to the presence of a magnetic field. Some dive watches include multiple gauges that measure elapsed time on the bottom, and have alarms that flash or vibrate so you can sense them even when water muffles sound. It’s also required to withstand a blow from a 6.6 pound (3 kilogram) hammer at an impact velocity of 14.4 feet per second (4.4 meters per second).