Caddie did what he said, balancing herself with a hand on his shoulder while she pulled a fin onto one foot. It went on more easily than she expected, and she tightened the strap around her ankle with a satisfied tug. This is going to be a piece of cake, she told herself as she put the second fin on.

“Now we’ll walk in,” said Brian. “But you’ll have to walk backward because you have fins on, so you’ll have to trust me.”

Her arm through Brian’s, Caddie shuffled awkwardly toward the ocean. Unable to see anything, she had to rely on him, which she didn’t like. It made her feel helpless. It’s just until we’re in the water, she told herself.

She felt the water hit her legs. As they proceeded, it rose to her waist, and then a wave crashed lightly against her lower back. At the same time, she felt water begin to seep into her wet suit. Now she was cold, but only momentarily.

“Okay, you can turn around,” said Brian.

Caddie turned, moving her finned feet carefully. She was in the ocean. Although the beach was less than fifteen feet behind her, she had the sensation of being in another world. Water was all around her. She looked down through her mask and saw the sandy bottom. A crab scrabbled away from her fin on tiny legs.

“We can swim the rest of the way,” said Brian. “Just put some air in your BC so you don’t sink.”

Caddie, remembering what he’d shown her, pressed the smaller of the two buttons on the inflator and felt her BC swell around her. When it felt full enough, she stopped. Brian had put his snorkel in his mouth, and she aped him, finding it where it was attached to her mask strap and slipping the end in her mouth. Then, falling forward, she swam.

She’d snorkeled before, but only in warm water. This was different. As they moved to deeper water, the landscape beneath them changed dramatically. The sand gave way to rocks, and then to areas thick with kelp. It really does look like the exhibit at the museum, Caddie thought. It’s beautiful.

After a minute she felt something tug on her arm and looked over to see Brian floating vertically in the water. She lifted her head, bobbing, to see why he’d stopped.

“We’ll go down here,” Brian told her.

“How do I do that?” Caddie asked.

“Just let the air out of your BC,” said Brian. “Like this.” He put his regulator in his mouth, held his inflator hose up, and pressed a button. Air hissed out, and a moment later Brian began to sink out of sight. Caddie watched his head sink beneath the surface.