Stranded on an island with a blond

Once, there were three people stranded on a deserted island, a redhead, a blonde, and a brunette. The closest civilization was 20 miles away. They decided that their only hope was to swim back to the mainland.

The redhead swam out 10 miles, got tired, and drowned.
The brunette swam out 15 miles, got tired, and drowned.
The blonde swam 19 and 5/6th miles, got tired, and swam back to the island.

This joke is filed under Blonde.