Point Reyes National Seashore encompasses approximately 71,000 acres of field, forest and shoreline along the Pacific coast north of San Francisco. There are nearly 80 miles of shoreline along the coast and an additional 18 miles in the large estero systems. This interface between the aquatic and terrestrial environments provides prime haul-out and breeding sites for several species of seals and sea lions. The adjacent marine waters (which include two National Marine Sanctuaries) support at least 20 species of whales and porpoises that can sometimes be seen from the mainland.