Apple Watches are water-resistant, but not waterproof. This means that they can withstand some water, but they are not designed to be submerged in water or exposed to sustained water pressure
The Apple Watch Series 2 and later have a water resistance rating of 50 meters (about 164 feet) under ISO standard 22810:2010. This means that they can be used for shallow-water activities like swimming in a pool or ocean, but they should not be used for diving or other activities involving submersion below shallow depth or high-velocity water.
The Apple Watch Series 1 and Apple Watch (1st generation) have a water resistance rating of IPX7 under IEC standard 60529. This means that they can withstand water splashing from all directions, but they are not protected against water jets or immersion.
It is important to note that even though Apple Watches are water-resistant, they are not immune to damage from water. If your Apple Watch gets wet, it is important to dry it off as soon as possible. You can do this by wiping it down with a dry microfiber cloth and letting it air dry. Do not try to dry your Apple Watch with a hair dryer or other heat source.