America’s largest national seashore spans two states and 80% of it is underwater

It’s America’s largest national seashore

Gulf Islands National Seashore runs 160 miles from Cat Island, Miss., to the Okaloosa Area east of Fort Walton Beach, Fla. Congress established it in 1971, and it holds the title of the largest national seashore in the country.

You get barrier islands, maritime forests, salt marshes, bayous and historic forts spread across two states, separated by Alabama in between.

Over 80 percent of the park sits underwater, and the marine life down there is the part most people never think about.

Five flags flew over this deep-water harbor

Spain, France, Britain and the United States all wanted the deep-water harbor at Pensacola Bay. Fort Pickens on Santa Rosa Island took 21.5 million bricks to build and stood finished by 1834.

It held for the Union through the entire Civil War, one of only four Southern forts to do so. Apache leader Geronimo spent time there in 1886-1887 before a transfer to Alabama.

Across the bay, Fort Barrancas went up in 1844 with 6 million bricks on a bluff where fortifications had stood since the late 1600s.

The sand came from the Appalachian Mountains

The white sand under your feet started as quartz in the Appalachian Mountains. Rivers carried it to the coast over thousands of years, grain by grain.

The barrier islands themselves formed in the last several thousand years after sea levels settled following the last ice age. Sand dunes line the south-facing shores, and some of them rise well above your head.

Gentle waves, tides and storms keep reshaping everything, so the coastline you walk today will look different next year.

Opal Beach has emerald water and no crowds

Opal Beach on Santa Rosa Island gives you powdery white sand and water that runs emerald green. You get open views in every direction, and the crowds thin out fast compared to the commercial beaches nearby.

If you want even more quiet, head to Johnson Beach on Perdido Key, where a discovery nature trail winds through the dunes behind the shore.

Langdon Beach near Fort Pickens sits in calmer water, and you can see the outlines of old gun batteries right along the sand.

Take the ferry 12 miles out to Ship Island

West Ship Island sits about 12 miles off the Mississippi coast, and you reach it by passenger ferry from Gulfport. Hurricane Camille split the island in two back in 1969.

The Army Corps of Engineers started a project in 2017 to stitch the halves back together and closed the breach in 2019.

Once you land, you can walk through Fort Massachusetts, a curved brick fortress built between 1859 and 1866. French explorer Pierre Le Moyne d’Iberville charted this island in 1699 while mapping the Mississippi River.

Horn Island has no roads and no buildings

Horn Island and Petit Bois Island earned wilderness status in 1978, protecting about 4,080 acres between them. These are some of the last undeveloped barrier islands left on the Gulf Coast.

You can only reach Horn Island by private boat, and once you land, there is nothing. No roads, no buildings, no bathrooms.

You pitch a tent on the beach and that is your camp.

Primitive camping runs up to 14 consecutive days, so you can stay long enough to lose track of what day it is.

Over 300 bird species stop along these islands

More than 300 documented bird species live in or pass through the park. Osprey, bald eagles, great blue herons and falcons build nests in the treetops along the shoreline.

Down on the sand, black skimmers and tiny least terns lay eggs during the warmer months. Every winter, hundreds of migratory species land on these barrier islands on their way south.

The Davis Bayou area in Mississippi draws birdwatchers for its marshland, where you can spot wading birds from the trail without scaring them off.

Sea turtles dig nests from May through October

Four species of sea turtles come ashore to nest on park beaches: loggerhead, green, Kemp’s ridley and leatherback. Loggerheads show up the most, and nesting season runs from May through October.

The park also protects the Perdido Key beach mouse, a tiny endangered creature that lives nowhere else on Earth.

Out in the water, bottlenose dolphins and cownose rays cruise along the sandbars where you can spot them from shore. Head inland to Davis Bayou in Mississippi, and you might see alligators in the marsh.

Paddle through salt marshes with dolphins below

Kayaking and paddleboarding work well in both states, with calm launch points at Davis Bayou, Santa Rosa Sound and Naval Live Oaks.

You glide through salt marshes and the water is shallow enough to watch dolphins, stingrays, pelicans and sea turtles move beneath you.

Naval Live Oaks sits on a strip of land between Santa Rosa Sound and Pensacola Bay, so you can launch from either side depending on the wind. Go in the morning.

The water is calmest then, and the marine life is easier to spot.

Cast a line from the beach, pier or boat

You can fish from beaches, piers or boats across the park, and the variety of spots keeps things interesting. Redfish, speckled trout and flounder are the common catches.

The Davis Bayou area in Mississippi has its own fishing pier and boat launch, so you can get on the water fast.

Over in the Fort Pickens area, miles of shoreline give you both pier fishing and surf fishing in the same trip. Bring a valid state fishing license for whichever side of the border you plan to cast.

Spanish moss hangs over trails through old-growth oaks

The Fort Pickens area has a scenic loop that takes you through coastal dunes, maritime forests and past old military structures.

Over in Mississippi, the Davis Bayou Trail covers about two miles through coastal forest and crosses two bayous along the way.

Naval Live Oaks, purchased in 1828 as America’s first federal tree farm to supply live oak timber for Navy ships, now has miles of hiking and biking trails under some of the oldest federally protected trees in the country.

Spanish moss drapes from the branches overhead on most of these paths.

Fall asleep to waves at Fort Pickens Campground

Fort Pickens Campground on Santa Rosa Island puts you on a barrier island between Pensacola Bay and the Gulf.

Sites come with water and electrical hookups for tents and RVs, and sand scrub oaks and pine forest surround the grounds.

In Mississippi, Davis Bayou Campground in Ocean Springs has 52 sites among live oaks and pine trees next to a saltwater marsh.

If you want something wilder, primitive camping is open on Horn, Petit Bois, East Ship and Cat islands, plus east of Johnson Beach on Perdido Key.

Explore Gulf Islands National Seashore in Florida and Mississippi

You can start from either state. The Florida district headquarters sits in Gulf Breeze, and the Mississippi district headquarters is in Ocean Springs.

Visitor centers are at Fort Pickens, Fort Barrancas, Naval Live Oaks and the William M. Colmer Visitor Center at Davis Bayou.

If you plan to see Fort Barrancas, it sits inside Naval Air Station Pensacola, so bring a valid photo ID for the military security checkpoint. The park stays open year-round, and the ferry to West Ship Island leaves from Gulfport, Miss.

This article was created with AI assistance and human editing.

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