Occasionally, open water swimmers compete in locations where the local government authorities do not want people to swim. As we travel the world, we notice signage posted at open water swimming venues.
To the left is a warning sign at the Olympic 10K Marathon Swim course in Beijing - with the swimmers racing in the background.
The photo on the left shows an official warning sign in Dubai in the United Arab Emirates.
Professional marathon swimmers are racing between the escort boats in the background.
But, Richard Clifford, an experienced open water swimming kayaker from New York, brings us a seriously dangerous hole located near Manhattan Island.