Santa Cruz and flight to Quito

These are not volcanic craters but sinkholes, holes where the ground fell in. The roof of an empty space under the ground (a lava tube) broke and fell inward. Each hole is about 30 m deep, with steep, straight walls.

The trees around them are Scalesia, from the sunflower family. On an island far from other land, with no other trees to compete with, they grew up to 15 m tall. This is called "insular woodiness": small plants on islands grow into trees. About 15 Scalesia species developed here from one shared ancestor.

An adult giant tortoise can weigh up to 250 kg and live more than 100 years. About 15 subspecies developed apart from each other, with two main shell shapes. On wet, grassy islands the shell is round like a dome. On dry islands it is shaped like a saddle, and the tortoise has a long neck.

From 1965 the Charles Darwin Research Station ran a program to breed tortoises in captivity. It has released more than 7,000 tortoises into the wild. Lonesome George, the last giant tortoise of the Pinta species, died in 2012 with no young.