Baltra Island, also known as South Seymour, is the gateway through which most people enter and depart the Galapagos Island. Upon arrival and once through immigrations procedures, visitors are transferred directly to a nearby dock to join the ship by Zodiac. The runway was first constructed here during World War II when the island was used as a US Army Air Base. Located near the geographic center of the Galapagos, the island itself is small, flat and arid. Its dry environment hosts salt bushes, prickly pear cactus and palo santo trees, all of which support land iguanas that can occasionally be seen crossing the runway.