Isabela Island, also known as Albemarle is the largest island in the Galapagos. This 1,800sqft island is more than 100km long and lies on the western edge of the archipelago. Six volcanoes flowed together and formed Isabela, some of them as high as 1,700m (5,600ft). The Sierra Negra Volcano, located on Isabela, has the second largest crater in the world, measuring 10km (6 miles) in diameter. The visitor attractions on the island provide for an exhilarating eco-adventure. While on a nature walk, discover a slat water lagoon, a scenic overlook, and a spectacular view of lava fields, volcanic formations, and the ocean. In the north of Isabela there is a small promontory known as Punta Vicente Roca, which presides over a pair of coves, on the southwestern edge of Volcano Ecuador. The surrounding cliffs are actually the interior walls of a fallen volcano and there is a partly flooded cave. At this location, a wall dive will take you into the shallow undersea cave. Here you will encounter the Port Jackson or Horned Shark, which is a species of bottom shark. The wall hosts an incredible variety of sponges, corals and many other invertebrates, displaying its abundant ocean life which is the product of cool, nutrient-rich waters up welling off the volcano's steep submarine slopes. A well known site on the island, Tagus Cove, was a prime destination for pirates and early whalers in the early 1800’s. Historical Graffiti dating back to this time can be found on the rocky cliffs of the cove. The amazing wildlife found on the island can satisfy the most eager naturalists. Sea lions, flightless cormorants and blue footed and masked boobies will most surely be encountered.