Tower (Genovesa) is a low volcano barely breaking the surface of the ocean. Ships sail directly into its large breached caldera to anchor at the foot of the steep crater walls. It attracts vast numbers of pelagic seabirds who come here to nest. Great frigate birds, red-footed boobies, swallow-tailed gulls and storm petrels all breed here by the thousands. A trail leads from a coral beach past tidal lagoons where lava gulls and yellow-crowned night herons are seen, then along the low shrubs populated by frigates and boobies, and eventually to a cliff edge where seabirds soar. A second trail leads to an open area for masked boobies, more frigates, and red-footed boobies. At the end of the trail thousands of band-rumped storm petrels flutter at the cliff's edge, where they nest in crevices. Short-eared owls can sometimes be seen here, hunting the storm petrels during daylight hours.