Once a hideout for British buccaneers and one of the stops on Darwin’s itinerary, Isla San Santiago is the fourth largest of the islands. Its terrain of rough lava fields is an example of the island’s challenging beauty. It’s a frequent stop on boat tours because of its variety of wildlife and there are several interesting visitor sites, including Puerto Egas, named after the owner of what was once the country's only salt mine.
Sullivan Bay is on Santiago's east coast. Here, a huge, black, century-old lava flow has solidified into a sheet that reaches to the edge of the sea. A dry landing enables visitors to step onto the flow and follow a trail of white posts in a 2km circuit on the lava. Volcanology or geology junkies will rejoice at the sight of uneroded volcanic formations such as pahoehoe lava, lava bubbles and tree-trunk molds in the surface.