Grand Isle State Park, State park and beach on the Gulf of Mexico, Louisiana, US

Grand Isle State Park occupies a sandy shoreline along the Gulf of Mexico with a long fishing pier jutting into the water. The grounds include beachfront camping areas and facilities such as bathhouses and utility hookups for visitors.

Grand Isle is Louisiana's only inhabited barrier island, and the state park at its eastern tip has been reshaped by Gulf storms. Hurricanes Katrina (2005), Gustav and Ike damaged the park, and the fishing pier destroyed by Katrina was later repaired. In 2010 the beach closed after Deepwater Horizon oil reached it, reopening in part on May 3, 2011; the next month volunteers planted 1,600 black mangroves against erosion.

Grand Isle is the only inhabited barrier island in Louisiana, and the park sits at its eastern tip. The area holds a long-standing reputation as one of America's best fishing spots, with access to over 300 species of fish. Local lore also includes the legend of the rougarou, told as part of the island's history.

The park sits at the eastern tip of Grand Isle, about 4 km northeast of the town of Grand Isle, reached by Louisiana Highway 1 across the island. The fishing pier destroyed by Hurricane Katrina in 2005 was repaired, and an observation tower gives views over the coast. Beach restoration is ongoing, so some shoreline may be closed.

The park is rumored to hold the buried treasure of 18th-century privateers Jean and Pierre Lafitte, whose operations were based at Grand Terre Island across Barataria Pass. Local history also includes the legend of the rougarou. In 2020 The New York Times listed the site among 52 Places to Go, noting it may soon vanish.