Is the Apple Watch waterproof?
Apple Watch Series 4 is listed as having a "water resistance rating of 50 meters under ISO standard 22810:2010." This means it is safe to submerge your Watch in shallow-water when showering or swimming. It is not recommended that you take your Watch scuba diving, waterskiing, or on other activities that involve "high-velocity water or submersion below shallow depth."
The Apple Watch Nike+ and Hermès are also Series 4 models and carry the same water resistant rating of 50 meters under ISO standard 22810:2010.