"The Tijuana River National Estuarine Reserve is located south of San Diego and within view of Mexico. The reserve comprises 2,531 acres of salt marshes, tidal wetlands, mud flats, brackish ponds, vernal pools, riparian habitat, dunes, upland areas, and sandy beaches within the Tijuana River floodplain. The Tijuana River delta is the largest and most diverse wetland in southern California, supporting a wide variety of plants, shorebirds, over 370 species of migratory and resident waterfowl, invertebrates, and fish. Within the reserve is Border Field State Park, located at the United States-Mexico border, and the Tijuana Estuary National Wildlife Refuge in Imperial Beach. Many areas are off limits, but an established 6-mile trail system allows public access while still protecting sensitive estuarine sanctuary. The trails cross the relatively flat terrain, meandering around the open and protected waters. This hike loops through the wildlife refuge, adjacent to the Imperial Beach Naval Auxiliary Landing Field."