On North Seymour and Española, male boobies court by lifting their bright blue feet one at a time, whistling, and pointing their beaks to the sky. The bluer the feet, the better the catch, and they're happy to show off while you watch from the trail.

In the green, misty highlands, giant tortoises weighing more than 500 pounds graze through pastures and soak in muddy ponds. You walk among them with your guide, then stop at a nearby farm for a cup of coffee grown right on the island.

Young sea lions are the islands' great entertainers. Slip into the water and they'll spin, blow bubbles, and swim straight toward your mask before darting away, clearly delighted with themselves.

The Galápagos penguin is the only penguin that lives this far north in the wild. You snorkel beside them below Pinnacle Rock, then climb the wooden boardwalk to the summit for the most famous view in the islands.

On the youngest island in the archipelago, hundreds of marine iguanas, the world's only seagoing lizards, warm themselves on fresh lava. Nearby, flightless cormorants dry their stubby wings after diving for fish along the shore.

Nearly the entire world's population of waved albatross nests on this one island. From April through December, pairs greet each other with an elaborate dance of bill-clacking and sky-pointing on the cliffs of Punta Suárez, while a blowhole sends sea spray high into the air below.

Two towering rock walls rise from the open sea, with a narrow channel running between them. You snorkel through as sea turtles, rays, and reef sharks glide below, and on lucky days a school of hammerheads passes through the blue.

Reached by an overnight voyage, Genovesa is a crater island alive with seabirds. Red-footed boobies nest in the shrubs, frigatebirds puff out their scarlet throat pouches, and short-eared owls hunt in broad daylight along the cliffs.

Hike across the highlands of Isabela to the edge of one of the largest volcanic calderas on Earth. The view stretches across miles of black lava fields to the sea.

A panga glides through the still mangrove lagoons on Santa Cruz's northern shore, where sea turtles surface beside the boat, golden rays drift by in formation, and white-tipped reef sharks rest in the shallows.

At the harbor fish counter, sea lions and brown pelicans wait patiently beside the fishermen for a share of the morning catch. Afterward, visit the Charles Darwin Research Station to learn how scientists are bringing tortoise populations back from the brink.