Last location of Iwatch with dead battery.
My Apple Watch is lost and has no power to send lost signal. How can I get last location?
Apple Watch, watchOS 4
If your watch was set up in your Find my iPhone collection you have a 24 hour visibility window after it was last seen on the network. After that it is not displayed by Find my iPhone and you have to search the old fashioned way with Mk1 Human Eyeball.