Unless it has a screw down crown...fahgeddabouddit! The seal at the crown and moreover the function buttons will give you trouble, especially if you try to operate them frequently in these situations. Soap, shampoo, body washes, ect, under hot water exacerbate the issue. I've tested a number of premium 5 Bar rating watches in Hawaii with surface swimming, light snorkeling, surfing, and topping off with hot showers, steam rooms, and nice long soaks in the jacuzzi. 9 out of 10 fail these real world tests at 5 Bar.
If you notice the very similar Japanese models get 10 Bar. Why? They know better. Onzens are part of their culture and the only thing they wear in the Onzen is their watches!