Fear and floating in the Caribbean

Thursday, 3 p.m.: Gearing up

It's a fine April afternoon in the Bahamas, and I'm at the checkout counter inside Sunn Odyssey Divers, receiving equipment for a nerve-jangling assignment: help an NFL star cross "shark encounter" off his bucket list, with guidance from Discovery's Shark Week team. It's a tall order for me, a guy who wakes up afraid most mornings, and I'm second-guessing my life choices as Rob Gronkowski barges through the glass doors.

"What's up, Sam!" exclaims the ever-exuberant Gronk, who has been whisked straight here from the airport. The Patriots tight end looks carefree, per usual, like a guy who lives the life we would all want to live if we were rich, 29 and had a…