Covering about 163 square miles, an area about the size of the island nation Barbados, Gatún Lake extends northwest from Parque Nacional Soberanía to the locks of Gatún, just south of Colón. The lake was created when the U.S. government dammed the Chagres River, between 1907 and 1910, so that boats could cross the isthmus at 85 feet above sea level. By creating the lake, the United States saved decades of digging that a sea-level canal would have required. It took several years for the rain to fill the convoluted valleys, turning hilltops into islands and killing much forest (some trunks still tower over the water nearly a century later). When it was completed, Gatún Lake was the largest man-made lake in the world. The canal route winds through its northern half, past several forest-covered islands (the largest is Barro Colorado, one of the world's first biological reserves). To the north of Barro Colorado are the Islas Brujas and Islas Tigres, which together hold a primate refuge—visitors aren't allowed. The lake itself is home to crocodiles—forego swimming here—manatees, and peacock bass, a species introduced from South America and popular with fishermen. Fishing charters for bass, snook, and tarpon are out of Gamboa Rainforest Resort.