In a Sauna or Steam Room
Again, water resistance isn’t waterproofing. But even then, the main problem with wearing an Apple Watch into a sauna or steam room isn’t the water. Instead, it’s the heat.
Overheating can cause all sorts of permanent damage to electronics, including to their batteries. Because of that, we recommend taking off your Apple Watch before getting into a steam room, taking a hot yoga class or stepping into a jacuzzi, hot tub or warm bath. This advice also goes for any particularly hot environment. Don’t charge your Apple Watch in direct sunlight or in significantly high ambient temperatures.