Hmm, I'd like to see a couple of their 'Tough Solar' models. When I went to get the battery replaced for my old G-Shock watches in the past, they always managed to screw up the watertight seal.
pixllThe guy replacing my battery said that replacing the battery WILL break the watertight seal. There was only like pieces of rubber on the inside I recall.
foRiReIt's an O-Ring. That is something that is almost universally used to keep out water. Simply screwing two pieces of metal together does not keep out water. Capillary action ( https://en.wikipedia.org/wiki/Capillary_action ) will pull the water along the threads.