One fateful morning in March 1997, I was the last person to board a boat and find the last open seat on one of the long white benches that ran down each side of the open skiff. As the boat pulled away from the dock in Bocas del Toro, Panama and headed for the offshore reef, I noticed the tall man next to me. From the clean, simple cut of his attire, I guessed he was European.

“My name is Dieter,” he said, speaking loudly over the roar of the outboard motor...