Galapagos Island Explorer

Baltra shows up low and dry after 600 miles of open Pacific. A ferry across the Itabaca Channel puts you on Santa Cruz and the road climbs into green: at Los Gemelos the ground has fallen away twice, two sinkholes in the scalesia forest where the roof of a lava chamber gave out. Lunch is up there, and the last stretch is a boat across the bay to a hotel with no road to it.

A mile and a quarter of cobbled path through cactus forest opens onto Tortuga Bay, a long crescent of white sand with marine iguanas asleep across it and nobody moving them along. The surf end is for walking; the sheltered lagoon at the far end is where you swim, among rays and young sharks in water that barely reaches your chest. The afternoon is the Charles Darwin Station, where the tortoise breeding pens hold the hatchlings of the island races that came closest to going out.

The yacht leaves early, because the islands worth reaching are two or three hours out and the day is built around getting there while the light is still low. What you land on depends on which island the park has open that day, and each one keeps a different animal: frigatebirds inflating scarlet throats, land iguanas the colour of the rock, a beach of sea lions that will not move for you. Snorkelling comes off the back of the boat before lunch, and the crossing home is the part people remember.

The morning climbs to Cerro Mesa, a crater in a private reserve where the scalesia forest holds most of the island's small land birds, finches included, close enough to tell apart. The afternoon drops to El Garrapatero, fine sand with a brackish lagoon behind it. Flamingos feed in that lagoon, and the brine shrimp they filter out of it are what turns them pink.

A short crossing puts you at the mouth of a mangrove channel where the water goes flat and the engine has to stop. The rest is paddled: green turtles surfacing off the bow, golden rays moving in formation under the hull, blacktip sharks in the shallows that want nothing to do with you. The mangroves are the nursery for all three, which is why boats stay out of the channel.

Twenty minutes inland the lava gives way to farmland and mist, and the giant tortoises are simply in it, on somebody's pasture. They come up from the coast for the wet season and nobody herds them, which is why you see them here rather than in a pen. A lava tunnel runs under the same land, wide enough to walk upright.

The boat back across the bay goes early enough for the drive north and the channel ferry. Baltra was an American airbase in the war, which is why the flattest island in the group is the one with the runway on it.