Steve travels to Guyana and is the first person ever to look for creatures at the bottom of a roaring waterfall. To get there he must abseil down 240 metres of rope into the roaring unknown around the plunge pool. It is a paradise for frogs and, even though he is hundreds of miles from the ocean, it's a haven for crabs. But Steve also discovers that it is no place for humans. Drenched by freezing spray, we leave him sheltering under a flimsy tarpaulin in the middle of an electrical storm.