Pago Pago Harbor, a collapsed volcanic caldera is one of the largest natural harbors in the South Pacific. It cuts deeply into the south-central coast almost dividing the island in two. From east to west, a steep mountainous spine runs the 20-mile length of the island, punctuated in places by notable summits including Matafao Peak, Tutuila's tallest mountain at 2,142 feet; North Pioa Mountain, popularly known as Rainmaker Mountain, 1,718; and Mount 'Alava, the steep ridgeline looming to the north of Pago Pago Harbor, marking the south boundary of the park area. Mount Alava lies to the north of Pago Pago Harbor. A hiking trail along the maintenance road leads to the 1610 foot summit.