Hot Tubs are wonderful for relaxing and treating sore muscles but it is possible to overheat when staying in a hot tub for too long.
If you stay in the hot tub longer than 10 minutes at a time you can get heat related illnesses such as heat stroke and it can cause death eventually.
But before you die in the hot tub you would probably have to stay in the hot tub for 30 minutes to an hour before you actually got cooked enough on the insides to cause death.
But your overall health can factor into the time that it takes for you to die from the hot tub.
It's recommended to get out of the hot tub every 10 minutes and take a break from it before getting back into the hot tub again.