The park contains Monument No. 258, a concrete obelisk placed in 1894 to mark the boundary between the U.S. and Mexico.
It is one of the largest remaining coastal wetlands in Southern California, playing a vital role in water filtration for the region.
The estuary is a primary stop on the Pacific Flyway, hosting thousands of migratory birds annually.
The landscape has been significantly altered by sediment transport from the Tijuana River, creating dynamic coastal geography.
Parts of the park are co-managed by California State Parks and the U.S. Fish and Wildlife Service.
Border Field State Park Beach serves as the southwesternmost point of the contiguous United States, sharing a direct physical boundary with Mexico. The park protects the Tijuana River Estuary, a critical habitat for several endangered species, including the light-footed Ridgway's rail. Visitors can observe the permanent boundary monument that marks the division between the two nations. The beach area features rugged, undeveloped coastline and shifting sand dunes shaped by constant tidal influence. Due to its proximity to the Tijuana River, water quality frequently varies, and swimming advisories are common. The park is managed as part of the Tijuana River National Estuarine Research Reserve. The environment consists of salt marshes, mudflats, and beach dunes providing refuge for migratory birds.
The elevated overlook area providing a clear view of the border fence extending into the Pacific Ocean.
Check the official California State Parks website for current water quality warnings or beach access closures before departing.
Bring binoculars for birdwatching, as the estuary is a premier location for spotting rare shorebird species.
Wear sturdy walking shoes to navigate the soft, deep sand dunes and trails that may be uneven.
Do not attempt to swim or wade in the water without checking current public health advisories, as runoff often impacts water safety.
Vehicle access to the park entrance is frequently limited by tidal flooding or maintenance needs; check park alerts for gate status.
Stay on marked trails to protect sensitive dune vegetation and nesting wildlife; do not approach the border fence.
