Actually our skin cooks at boiling point, just like the flesh of any other animal. Lobster, beef, human, it's all the same stuff.
This is a list of temperatures (fahrenheit) and duration of time it takes to cause third degree burns. The moral of the story is: be careful in hot tubs, and set the thermostat on your hot water heater at a temperature low enough to not cause burns. You can really get hurt and burns are no fun.
155 degrees 1 second
148 degrees 2 seconds
140 degrees 5 seconds
133 degrees 15 seconds
127 degrees 1 minute
124 degrees 3 minute
120 degrees 5 minutes
100 degrees safe
ok, end rant.