As she followed the others into a coral gorge, she was thrilled by the number and variety of fish. They came in every size and shape and in colors more brilliant than anything on land. The coral was equally dramatic, with colors that rivaled the fish and in shapes that ranged from brainlike masses to antlerlike growths. Diaphanous sea fans waved sinuously in the current.

Distracted by the beauty, Marissa realized the others had disappeared. She hurried forward, rounding a large coral head. Wynn was stopped up ahead. She saw him reach into a net secured to his waist. When he pulled out his hand she saw that he held some baitfish. In an instant he was surrounded by batfish and parrot fish. He clearly wasn’t interested in these species because he waved them away. Instead he went close to the opening of a large underwater cave and began to wave the bait through the water.

Marissa’s heart leaped into her throat, almost causing her to spit out her mouthpiece. Out of the shadows of the cave swam an enormous six-foot, six-hundred-pound potato cod. Marissa was about to panic when she noticed that Wynn was not only unperturbed but was enticing the fish to come all the way out. Then to Marissa’s amazement, the huge fish took the baitfish directly from Wynn’s hand.

Wendy swam up behind Wynn and signaled that she wanted to try to feed the behemoth. Wynn gave her several baitfish and showed her how to hold them out.

The cod was happy to oblige, opening its huge mouth and sucking in the bait like an enormous underwater vacuum cleaner.

Wynn motioned for Marissa to swim over, but she was happy to stay where she was and indicated as much via hand signals. She watched Wendy feed the fish, but it was not easy to stay in one place. The surge from the wave action on the reef swept her to and fro, forcing her to fend herself off the coral with her gloved hands. The motion reawakened the queasiness she’d felt on the boat.

Once the potato cod had devoured all the baitfish Wynn was willing to offer, it lazily drifted back into its lair. Wendy went to the very lip of the cave and peered in. Then she swam back to Marissa and motioned for her to follow.

Reluctantly, Marissa swam after Wendy. They passed the cave’s mouth and dove close to the sandy bottom. Wendy pointed into a crevice, then backed away so Marissa could take a look.

Marissa hung on to the coral so the current didn’t pull her along as she let her eyes adapt to the shadows. She was glad she was wearing the heavy gloves. Finally Marissa saw what Wendy had pointed to: a large green moray eel with its mouth open and its needlelike teeth bared.