The park was acquired by purchase from Planet Oil and Mineral Corporation and Horizon Sales Corporation in 1972 and was opened to the public in 1977. The park is named for that portion of the Gulf shoreline where the marsh grasses extend into the surf in a zone termed Sea Rim Marsh. The park's coastline contains a biologically-important zone, wherein salt tidal marshlands meet the Gulf waters. These marshlands formed when silt from the Sabine River delta was carried down the beach by longshore currents. The park offers a marshlands airboat tour during the spring, summer, and fall.
Tours are by advance reservation only, last approximately one hour, and fees apply.
Airboat tours and canoe rentals are dependent on marsh water level and weather conditions. Fishing is permitted from dawn to dusk. Swimming is not permitted in the marshlands area, as alligators are present. The park is a prime wintering area for a variety of waterfowl common to the Texas Coast. Abundant wetlands wildlife include the American alligator, mink, nutria, raccoon, rabbit, opossum, skunk, rare river otter, and muskrat.