Galapagos Base Camp

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.

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.