Isabela is the largest island in the Galápagos archipelago, shaped by six shield volcanoes and home to Sierra Negra, one of the largest volcanic craters in the world. The town of Puerto Villamil offers a quieter, more laid-back base for exploring, with easy access to the Tintoreras islet — a narrow channel where whitetip reef sharks rest in shallow water alongside marine iguanas and penguins.

Further along the coast, Los Túneles is a striking network of lava-rock arches and pools, ideal for snorkeling with sea turtles, rays, and seahorses. Galápagos Xcursion offers day tours to Isabela combining Las Tintoreras, Los Túneles, and — for those with more time — the hike up to the rim of Sierra Negra's crater.