Garden Key is surrounded by the lapping ocean and, after the sun goes down, the nightly entertainment arrives. At first there are just a few pinpoints of light, then Venus is seen on the horizon. By the time you lie down to sleep, the stars fill the skies over Dry Tortugas National Park. The real show, though, is hours away.

My first day in Costa Rica’s famed Manuel Antonio National Park was, surprisingly, underwhelming. We set out to find sloths and Technicolor birds, but instead we were greeted by dense vegetation, a few spiders, and crowded beaches, with sand too hot to walk on. We left, not understanding what all of the hype was about—much like the first time I went to Yellowstone National Park and didn’t see a bison.