David Blaine. You probably haven't thought of him or his potentially fatal shenanigans lately, but you will soon think of nothing else. Your Google search history will be a witness! The illusionist/endurance artist just uploaded a video on his YouTube account that seems to show him swimming with a Great White shark. He wears a rotation of outfits: a tux, a Hawaiian shirt, and a red cape that looks distressingly like a pool of blood. Called "Dressed For Dinner" (get it? He is the dinner!), the video by directors Adam Kimmel and Bob Talbot comes with very little explanation, only the line: "David goes swimming with Great White sharks off the coast of Guadeloupe." Take a look below.
The bit about smoking a cigar underwater, as some commenters noted, seems a giveaway that Blaine is honoring his illusionist duties over his endurance artist ones. As for how the effect might have been done, this 1928 British video of a man smoking a pipe with the fishes offers an option.