America’s Longest Coastal Wilderness : Padre Island in Texas is an 80-mile highway of sand and shore with a speed limit of 25 m.p.h.

It felt just like a carnival thrill ride, I kept telling myself, as the big four-wheel-drive pickup bounced, slithered and plowed its way through axle-deep sand. Flung forward and back, my body strained at the seat belts as if to snap them. At the wheel was a young national park ranger, giving me an insider’s look at Padre Island National Seashore in Texas--one of the loneliest, loveliest beaches in America.

Lapped by the warm, blue-green waters of the Gulf of Mexico, the white sand stretches south from Corpus Christi for 80 miles, the country’s longest strip of still untouched, unspoiled coastal wilderness. That’s what drew me to the place: all those miles and nothing but sand and surf and sun.

Remote and mostly empty, much of the island is accessible only by foot or by four-wheel-drive vehicle over a single tricky road that runs alongside (and sometimes on) the beach, frequently snaring unwary drivers in hidden sand traps. Even our powerful truck seemed on the verge of bogging several times, and more than once the edge of a wave splashed against the tires.

To visit Padre today is to see the island much as the Spanish conquistadors did when they sailed past early in the 16th Century: a wide and seemingly endless beach backed by a low ridge of grass-topped dunes, and behind them flat wetlands and a shallow bay that these first explorers called Laguna Madre. Often on my ride south I could see no other sign of humanity except the faint track of the sandy path ahead and the ubiquitous oil-drilling rigs lining the horizon far offshore.

The most remote reaches of the parkland, “down island” where we were headed, are the domain of a relatively few hardy campers and fishermen who revel in the stark isolation. They spend their days relaxing under a burning Texas sun, splashing in the usually gentle waves, shell-collecting, bird-watching and surf-casting for redfish, whiting and sand trout. For 60 miles south of the visitor center, camping is permitted anywhere on the beach, and the farther south you go, the fewer people you find. Only the island’s fragile dunes are off-limits to hiking and camping.

But Padre is also a pleasant destination for the less adventurous. Fronting the visitor center at the seashore entrance is Malaquite Beach, where you can wade into the surf for maybe a hundred yards or more and still be only waist-deep. And the first five miles of the beach roadway south cover hard-packed sand capable of supporting recreational vehicles as well as ordinary cars, motorcycles and bicycles. Many campers simply pop up a sea-view tent next to their car for a night or two.

Meanwhile, the steady sea breezes wafting across Laguna Madre and its shallow depth--two to five feet--have made it a major windsurfing center, especially at the easily accessible northern end of the park. One afternoon, I counted more than 100 colorful sailboards in the calm blue water of a cove at Bird Island Basin. On the gulf side of the island, the same breezes draw kite-flyers.

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On my trip to southern Texas, which was in late March, I stayed in a bayfront hotel in Corpus Christi, a city of 235,000 about 35 miles northwest of Malaquite Beach. This gave me a chance to sample some of the region’s other attractions, several of which actually enhanced my enjoyment of Padre Island. At breakfast my first morning in town, I watched a parade of shrimp boats returning to port to sell their night’s catch just across from the hotel. Laguna Madre, I was to learn, is rich in shrimp and other sea life. Every restaurant in town features big fresh shrimp--fried, broiled, boiled, baked or grilled.

An attractive community, Corpus Christi is home to the Texas State Aquarium, a new and dramatically modern structure overlooking Corpus Christi Bay. It focuses appropriately on the marine life of the Gulf of Mexico. I watched a tankful of shrimp skittering about and learned more about their curious habits. Nearby is the Corpus Christi Science Museum, which features a fascinating exhibit displaying artifacts from a Spanish shipwreck on Padre Island in 1554. And one morning I took an informative 90-minute van tour of the famous 825,000-acre King Ranch in Kingsville, one of the largest cattle and horse-breeding operations in the world.

The huge and historic spread is located in lush, irrigated grasslands just 35 miles southwest of Corpus Christi. And what is the link between a ranch and a lonely island seashore? One reason Padre remained undeveloped is that for decades it was used for ranching, with the cattle roaming unfenced. A Portuguese priest, Padre Nicolas Balli, established the first ranching operation on Padre Island around 1800, when it was still a Spanish possession, and it is from him that the island gets its name.

For a time, the King Ranch, located just across Laguna Madre, owned acreage on the island. Today, much of this part of Texas, called the “Coastal Bend” for obvious geographical reasons, remains prime cattle country. On its Texas acreage, the King Ranch runs 50,000 cattle and 1,000 horses.

Shrimp and cattle and Spanish shipwrecks are an intriguing mix, but the big star of the Coastal Bend is Padre Island National Seashore in all its expansive and beautiful wildness. A visitor should exercise caution, however. Make a wrong turn on the rugged down-island drive, said Mary Griffith, my ranger escort, and it could cost hundreds of dollars to get pulled out of a sand trap. She knew what she was doing, and we plowed on without mishap.

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A slender island barely two miles across at its widest point, Padre is one of a chain of nearly 300 offshore barrier islands that protect the nation’s Atlantic and Gulf coasts from the ravages of storm-driven waves. Although it has been breached at its southern end by the man-made Mansfield Channel, Padre is still considered the longest of the barrier islands. Its two segments together cover about 113 miles, reaching south along the Texas coast from Corpus Christi almost to Brownsville on the Mexican border.

The national seashore occupies almost all of the northern three-quarters of the island, as far south as the channel. On the northern tip, there is some development just outside the seashore entrance, and it eventually could prove more intrusive than it is now. At that end, there also is a Nueces County beach park with a fishing pier. On the far tip of the southern segment, below the Mansfield Channel, is the bustling beach and condo resort town of South Padre Island, an object lesson in the value of wilderness preservation.

Padre Island National Seashore can be reached by land only from the island’s northern end. It is linked to Corpus Christi by a bridge and causeway across Laguna Madre. The road south is paved only as far as the visitor center, and then the route down-island takes to the beach. Any four-wheel-drive vehicle churning through soft sand is definitely a rude disturbance in the coastal quiet, and our truck was no exception. But a Texas law enacted before the national parkland was created reserves the state’s beaches as public roadways.

A light fog was lifting from the beach the morning I showed up at the visitor center, and a bright sun was about to peek through. A flock of “laughing” gulls, dozens of them strutting in the parking lot, greeted me with a chorus of angry squawks as they scattered. I sniffed the briny air and overheard a young couple bemoaning their plight. They had parked overnight on the beach, too close to the water. When the tide came in, washing around them, the car sank in the wet sand.

Inside, I met ranger Griffith, who is assigned to the seashore’s enforcement staff. She carries a revolver packed in a holster, but her days tend to be rather peaceful. Two primary duties are keeping people off the dunes and checking to see if any fishing regulations are violated. At least once a day, a ranger makes the full 60-mile drive down-island to Mansfield Channel, another of her routine tasks.

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On this morning, we would tackle the first 15 miles to Yarborough Pass, a cut in the dunes leading to a boating area on Laguna Madre, and then retrace our path. Barely out of the visitor center, we were waved down by a carload of bewildered college students bound for spring break in South Padre Island. Where was the party? they wanted to know. Griffith informed them they had made a wrong turn. True, they were on Padre Island, but the resort town was more than 100 miles south as the crow flies, and the only way to get there was to backtrack to the mainland. They faced at least another four hours on the road, grim news that they accepted fairly stoically.

For the first five miles over the sand, the speed limit is 15 miles per hour and the ride on the packed surface is smooth. Perhaps 30-40 cars and camping vehicles had ventured onto the beach for a mile or two and spent the night there, but in the dozen miles that followed we passed barely a handful of other parked vehicles. In the summer, the seashore is much busier, but usually there is plenty of open space between campsites.

At the end of the initial five miles, a sign warns that the rest of the way south can be made only in four-wheel-drive, and it isn’t kidding. Almost immediately, our truck began laboring, and Griffith had a full-time job keeping it moving through the sand. The speed limit now was 25 m.p.h., and we were bouncing without letup. A good driver can probably make the trip to Mansfield Channel in about three hours, Griffith said; the big sport there is shark fishing off the jetties.

Travelers down-island should take plenty of water. None is available south of the visitor center and if you get stuck, don’t ask the National Park Service for help. The rangers are not allowed to tow stranded vehicles. A typical pace, slogging through the sand, is about 10 miles a day.

I don’t know what I expected to find on Padre Island, and there really aren’t any sights that can be called especially spectacular. The beach widens and narrows, and the dunes are low here or a bit higher over there. But mostly, a sameness to the vistas prevails mile after mile. And yet in this sameness--the sky and the sand and the rolling waves in unceasing repetition--there is a compelling beauty. I envied the campers we were passing, and their solitude.

One unpleasant aspect of the seashore cannot be ignored. A sometimes unsightly amount of trash dumped into the Gulf of Mexico, some of it by freighters and other passing vessels, eventually washes up on the beach because of local wind and tide patterns. I spotted a couple of crates, a car tire, a fire extinguisher. Volunteers stage annual cleanup campaigns along a 10-mile stretch of the beach, and in one day last year they collected 30 tons of debris, much of it plastic.

In March, the sea breeze was chilly, and only a few people braved the water, which they said was “tolerable.” In summer, the water is almost as warm as a bath. The surf generally is fairly safe, said Griffith, although swimmers should keep alert for stinging jelly fish. And it is wise not to swim too far out because large sharks do meander by occasionally. On that note, Griffith deposited me back at Malaquite Beach, slightly jostled but otherwise in good shape after our 30-mile round trip down-island.

Now I wanted to see a bit of the island on my own, and I headed north on foot along a five-mile stretch of seashore where neither camping nor driving is permitted. In no time, I had left everyone else behind, and I had the beach to myself, except for little stick-legged sandpipers, flocks of sanderlings and the frenetic sand crabs.

There aren’t many places in this country these days where you can be alone with nature, and I sat on a piece of driftwood for a long time just watching the waves tumble in, enjoying the quiet.

GUIDEBOOK: Prancing to Padre Island

Getting there: The Corpus Christi airport serves Padre Island National Seashore. Delta, American and Continental fly from LAX to Corpus Christi, via Dallas on Delta and American, through Houston on Continental. With 14-day advance purchase and a Saturday stay-over, Continental is offering round-trip service for $200; flying must commence by Sept. 5, and tickets purchased by Aug. 31. The fare is $290 (also with 14-day advance and Saturday stay-over) on Delta and American.

When to go: The national seashore is open year-round. Spring and fall are pleasant, although hurricanes are a possibility in fall. Summer is hot, with an average high in the upper 80s. Winter is mild, with average highs in the low 60s. Winter is the only season the weather and water temperature are too chilly for swimming. As might be expected, most visitors go in summer.

Where to stay: Within Padre Island National Seashore there is only camping. Just north of the visitor center at Malaquite Beach, there are two campgrounds ($5 per night) available on a first-come, first-served basis for tents and recreational vehicles, with picnic tables, restrooms, cold showers and a sanitary dump station but no electrical or water hookups.

For 60 miles south of Malaquite Beach, visitors can camp for free anywhere on the beach in tents or RVs. The only facilities are occasional primitive toilets along the first five miles south.

Elsewhere on Padre Island: About 10 miles north of Malaquite Beach, outside the national seashore boundary, is the Holiday Inn Gulf Beach Resort (800-465-4329 or 512-949-8041), overlooking the Gulf of Mexico. A room for two begins at $106 a night for a limited view; a beachfront room is $135 a night.

In Corpus Christi, there are several hotels and motels downtown overlooking Corpus Christi Bay, among them the Marriott, Sheraton, Radisson, Ramada Inn and the Sand & Sea Budget Inn. At the high-rise Marriott, where I stayed, a room for two begins at $95 a night for two on weekends, $140 a night on weekdays. For a list of lodgings: Corpus Christi Area Convention & Visitors Bureau, P.O. Box 2664, Corpus Christi, Tex. 78403-2664, (800) 678-6232.

For more information: Contact the Padre Island National Seashore, 9405 South Padre Island Drive, Corpus Christi, Tex. 78418, (512) 937-2621.