Sea lions, usually a very curious lot, take a break. Photo / Supplied

Sea lions, usually a very curious lot, take a break. Photo / Supplied

When young Charles Darwin first landed in the Galapagos Islands in 1835 he was so disappointed by what he saw he is said to have considered re-boarding the HMS Beagle and hightailing it out of there.

The 26-year-old Darwin expected this small group of islands on the equator to be a lush tropical paradise teeming with wildlife, but what he encountered was barren, harsh and windswept. Not particularly inviting, even after months of debilitating sea sickness aboard the Beagle.

And landing at Baltra airport after an hour-and-a-half flight from Ecuador it's not hard to see how Darwin felt. This hot, windy, monochromatic place looks more like the Australian Outback than a tropical paradise. Luckily Darwin persevered, or he may never have come up with his theory of evolution.

Ever since, this intriguing land of few humans but many weird and wonderful animal species has attracted explorers and tourists.

Sea lions wander up to you on the beach like curious labradors and play with you when you're snorkelling. Marine iguanas don't flinch when you step over them, and giant tortoises lazily eye you as you meander by.

There are no predators in the Galapagos Islands, apart from the not-very-scary endemic hawk, so the animals evolved without the fear that most animals possess.

Marine iguanas of about 1m cover the rocks among the moon-like lava formations of Bartolome Island. These dragon-like creatures bask in the sun to warm up after their forays into the ocean and every so often noisily sneeze salt.

On nearby Rabida Island, the sand is a deep red - you could be on Mars, if it wasn't for the sea lions lolling on every inch of the beach.

On Espanola Island, more sea lions bask on the long, white sand beach. And up in the highlands you have to be careful not to trip over all kinds of strange birds, from nesting albatrosses to blue-footed boobies carrying out their curious mating dance.

How so many animals different from anything anywhere else in the world could end up on this isolated group of islands barely touched by humans is a puzzle. It certainly puzzled Darwin, but it planted the seed for what would become his theory of evolution. It wasn't until he was back in London studying the samples he had collected in Galapagos that it occurred to Darwin that living organisms adapt and modify until they become different species. In the Galapagos, the isolation is such that different subspecies developed on each island. There are, for example, 13 types of finch, each slightly but crucially different to the next.

After a quick boat ride across the channel to Santa Cruz, where most of the Galapagos' human inhabitants live, a bus ride to the island's centre shows how varied these islands can be. After 15 minutes or so along a road bordering barren terrain, the temperature suddenly drops and, almost incredibly, it starts to rain. The landscape turns from dry rocky plains into lush vegetation.