No lifeguard is on duty: swim 'at your own peril'. [='at your own risk']
The species is 'in peril' [=(more commonly) 'in danger'] of dying out.
Restaurants that ignore the smoking ban do so 'at their peril'.
(..) We do not have the strength to fight both Mordor and lsengard! Gandalf... ...the Ring cannot stay here. This peril belongs to all Middle-earth. They must decide now how to end it. The time of the Elves is over. My people are leaving these shores. Who will you look to when we've gone? The Dwarves? (..)2001 The Lord of the Rings: The Fellowship of the Ring