From the Apple webpage for Series 7 watch:
"Apple Watch Series 7, Apple Watch SE, and Apple Watch Series 3 have a water resistance rating of 50 meters under ISO standard 22810:2010. This means that they may be used for shallow-water activities like swimming in a pool or ocean. However, they should not be used for scuba diving, waterskiing, or other activities involving high-velocity water or submersion below shallow depth. Series 7 is also rated IP6X dust resistant."
Sounds to me as though these watches are not intended for what I'd call 'serious' frequent use in water. They do have the feature to remove any water that gets into the watch, but personally I'd be pretty hesitant to wear one of these watches while swimming.