The Laguna Madre is a large body of shallow water separating Padre Island from the South Texas mainland. It covers 609 square miles of estuarine and coastal marine systems. The boundary of Padre Island National Seashore encompasses approximately 20,000 acres of the Laguna Madre. Since no major rivers flow into the Laguna Madre, its salt content is quite high, about 35 parts per 1000 parts of water. This increases to 45 parts per 1000 parts of water in the Lower Laguna Madre and during periods of hot, dry weather. The average water depth is about 2.5 feet, with some areas reaching a depth of 5 feet. Variable depths and salinity support different types of seagrasses, hyper-saline marshes, algal flats, and lomas. Mudflats, barrier islands, dunes, spoil islands, saline marsh, and coastal sand plains are the main geomorphic features of Laguna Madre. Sport fishing is very rewarding in the Laguna Madre where redfish, black drum and flounder are caught. Texas General Land Office (GLO) operate fishing cabins as well as camping sites on the spoil islands. The Laguna Madre is a large area and parts of it are owned by the public sector while other parts are owned by the private sector. The Texas General Land Office (GLO), Texas Parks and Wildlife, and the federal government own a large section of the area, while private entities like the Audubon Society, King Ranch, and others own other sections of the area. The Laguna Madre is a unique area along the Gulf of Mexico in southwest Texas, and Port Mansfield is a great place to access much of it. Portions of the famous King Ranch extend north from Port Mansfield for many miles up along the coast, providing undeveloped waterfront as far as the eye can see. There are 550 square miles of water in the entire Laguna Madre. A good deal of it is far from major ports, which means there are places to fish by yourself if you're willing to make a run. Amazingly, the average depth here is just 3 1/2 feet. Specialized shallow draft boats are used. There is only small tidal movement in the lagoon, which is saltier than the ocean, and the clear water allows light penetration to grow abundant sea grasses. This combination provides a near year-round environment for seatrout (primarily spotted seatrout), redfish, and flounder. The water is generally clear, unless stirred up by persistent winds, and the bottom has lush greenery and white-sand holes, often producing large fish that lie in wait to ambush bait. Much fishing is done by stalking, using boat and foot to look for individual fish (mainly redfish) or schools of trout and reds.  Because virtually all this angling is done in very thin water, great light-tackle excitement can result. It's not uncommon for a group to catch several dozen fish in one spot. Padre Island National Seashore protects much of the remote Laguna Madre from the open Gulf waters beyond. The seashore encompasses Padre Island, the longest barrier island in North America, where anglers can use four-wheel-drive vehicles to visit over 40 miles of waterfront. There's good fishing along the surf for a potpourri of species, and September sees a lot of action thanks to abundant, and close, baitfish schools. Surveys done by the Coastal Fisheries Division of Texas Parks and Wildlife indicate that the lower Laguna Madre has the largest population of trout and redfish to be found along the entire Texas coast. And nearly 57 percent of all the trophy seatrout (30 inches or better) landed in Texas in the past 25 years came from the lower lagoon. Another 20 percent came from the upper lagoon.