Hi
Apple Watch is designed to work best in ambient temperatures between 32° to 95° F (0° and 35° C):
Keep Apple Watch within acceptable operating temperatures - Apple Support
Apple advises that it should not be used in environments such as a sauna or steam room.
When planning to get Apple Watch Series 2 wet, you can manually lock the screen first and then clear water from the speaker afterwards:
- Swipe up from the bottom of the watch face to open Control Centre > tap on Water Lock to lock the screen.
- When finished: turn the Digital Crown to unlock the screen and to clear water from the speaker.
If you forget to enable Water Lock beforehand, the watch remains water resistant and the watch can be locked and immediately unlocked after water exposure in order to expel any water from the speaker.
After exposing the watch to anything other than fresh water, be sure to clean your watch by gently rinsing it with warm tap water. The watch and band should be dried using a nonabrasive, lint-free cloth.
Note that leather and stainless steel bands (Milanese Loop and Link Bracelet) are not water resistant, so should not be submerged in water.
More information:
About Apple Watch water resistance - Apple Support