Humboldt Isles Expedition

The flight from the mainland lands on Baltra, a flat scrub island that was an American airbase in the 1940s and is now the archipelago's gateway. Park formalities and the transit-card check are done inside the terminal, and the crossing to the ship goes from there: nobody stays on Baltra, which has no town and nothing to see.

South Plaza is a quarter of a mile wide and tilted, so the whole island is one slope: prickly pear at the low edge, cliffs at the high one, and a ground cover that turns scarlet in the dry season. Land iguanas sit under almost every cactus waiting for a pad to fall, and this is the one place where they overlap with the marine iguanas enough to cross, so the hybrids walk the same trail as both parents.

Santa Fe's bay is white sand over turquoise shallows with a sea lion colony along it, and the trail above runs through a forest of prickly pear grown tree sized, trunks and all. The land iguana under them is paler and larger than the ones on the other islands and lives on this one alone, which is what happens when a population is left by itself long enough.

The breeding centre at Cerro Colorado sits in the green south of San Cristobal and raises the island's own race of giant tortoise. Hatchlings are held until their shells are hard enough to survive introduced rats, then released into the hills above, and the enclosures are laid out so the released ones wander back through on their own.

A trail climbs a wind-carved ravine on the eastern tip of San Cristobal to the only ground in the islands where all three boobies nest together: blue-footed on the open trail, red-footed in the shrubs, Nazca along the cliff. Each keeps to its own layer, which is how three species that eat the same fish share one headland.

Cerro Brujo is a long white beach of eroded coral on San Cristobal, one of the few places Darwin himself came ashore in 1835. Sea lions sleep along the whole length of it, rays work the shallows a few feet out, and a lagoon behind the sand holds wading birds.

Espanola is the oldest island in the archipelago and the flattest, which is why the seabirds own it: no highland means no cover for anything that hunts them. The trail crosses marine iguanas flushed red and green in breeding colour to a blowhole throwing spray a hundred feet off the cliff edge, and from April through December the entire world population of waved albatross nests along this one headland and launches off that cliff to feed.

Gardner Bay is a mile of white coral sand with a sea lion colony spread the whole length of it and no shade, so the animals simply lie where they land and let people walk around them. The water is flat enough for kayaks and paddleboards, and the snorkeling is off the islet at the end of the beach, where the rock drops away and the fish stack up against it.

The station above Puerto Ayora is where the tortoise races that came closest to disappearing were pulled back, one island at a time, and the breeding pens hold hatchlings from the ones still being rebuilt. The rearing enclosures are laid out by island of origin, which is the clearest illustration in the archipelago of how far one species diverged across a few dozen miles of water.

Breakfast aboard, then the last disembarkation of the trip and the road north across Santa Cruz to the channel, the ferry over it and the short run to the airstrip on Baltra for the flight to the mainland.