It's not yet clear what the stakes here are. Will Phelps and the shark vie for a prize at the end of the racecourse? Just how close will Phelps get to this shark? How big and how terrifyingly toothy will the champion shark be? Will a last-minute reveal show, once and for all, that Michael Phelps, in fact, is a shark, in what would probably be the greatest example of shark-related television mythmaking since the days of Jabberjaw? When reached for comment with questions like these, Discovery told us it was too early to reveal more details.
What we do know from Phelps' Instagram is that the Olympian, shark-in-disguise or not, is definitely still alive. He's recently shared photos of himself and his wife together, as well as a tantalizing image of roast beef (which any shark would totally jump on, just saying).
He also shared this image five days ago, however: