During the deep dive of the watch, with the increase of water pressure, tiny helium molecules will be squeezed into the case from the gap of the watch under the action of strong pressure. The internal and external pressure of the watch is basically balanced, so that the watch can be well waterproof in the deep sea and prevent the glass from breaking and the case deformation. During the floating process, the external water pressure decreases rapidly, and it is difficult for the helium molecules in the case to be eliminated instantly, resulting in a huge pressure difference, which is enough to push the watch glass up!In order to solve this problem, all deep-dive watches are equipped with a helium escape device, so as to quickly remove the helium molecules in the case during the ascent process, keep the internal and external pressures equal, and ensure the normal operation of the watch.