These guys are one of the ‘flagship species’ of the Galapagos islands. It is believed they have evolved from the Land Iguanas who most probably floated to the island on driftwood.
They go in to the sea and dive down to eat the algae on the rocks. They don’t really like it though and get out as soon as they can to perform their infamous ‘snot rocket’ to get rid of the sea water.
I will post a picture of the snot rocket in action shortly.