I would personally keep any watch away from water unless it is sold as diving equipment. No matter how water resistant or water proof it is supposed to be. I'd interpret "water proof" as "no need to panic if you forget to take it off in the shower", but would never intentionally leave it on in the water. But that's just me.
(There was a sad/funny story on another website about a young person buying a Samsung Galaxy phone, being told in the shop that it was water proof, and when she took it for swimming, it was not. It turned out that back when this particular phone was the most expensive Samsung phone, it was water proof. New cheaper models with the same name were not. )