Video at link.French free diver Guillaume Nery jumped into the largest sinkhole on Earth with no scuba gear, no snorkel, no gear of any sort. Just a pair of massive, rock hard cojones. "Dean's Blue Hole" is a 663-ft deep sinkhole in the Bahamas. A couple helpful little factoids to aid you in understanding the gravitas of Guillaume's dive. The average human being can hold their breath for 45 seconds - or a minute if they have an exceptionally healthy set of lungs. After that, your body essentially starts to suffocate, as cells in your organs shut down from lack...