Galapagos, BBC One

The Galapagos archipelago is renowned as one of the richest, most biodiverse habitats on earth, with many species that aren't found anywhere else. It's also one of the most documentary-prone natural wonders.

Yet surprisingly little is known about these Pacific islands – why there are quite so many endemic species, why the terrain on each island is so different, and what's happening on the sea-bed, 1km below the surface. This three-part series aims to provide some of the answers.

Multi-talented animal biologist Liz Bonnin joins scientists leading the investigation – this week focusing on the Wolf Volcano on the youngest, and most volcanically active, western edge of the archipelago.

She travels on foot, by helicopter and ship, with a snorkel and in a deep-sea submersible, to witness cutting-edge research, meet species new to science, and visit habitats that only a handful of people in the world have ever seen.

There are also pink iguanas. As in highlighter-pink.

In a nature broadcasting world dominated by Sir David Attenborough, it's refreshing to see a documentary that focuses as much on the research as on the animals themselves. Much of it is geared towards learning how to protect species about which so little is known, but there's also a segment on shrinking sea-iguanas, and a reassuring appearance by some giant tortoises.

Next week: sunfish, sea lions and sharks. Lots of sharks.