With Tropical Storm Issac taking aim on the Gulf Coast, national parks and seashores in its path are battening down and getting ready to ride out the storm.

As early as this past Friday parks in Florida -- Everglade, Biscayne, and Dry Tortugas -- began closing facilities. At Everglades, the park (including Gulf Coast, Shark Valley, and Flamingo Visitor Centers, East Everglades, & the Main Park Road) was closed to visitors as of 8 p.m. Friday.

At Biscayne, park officials instituted a temporary shutdown at 5:30 p.m. Friday in accordance with its hurricane plan. All "park islands (including Boca Chita Key, Elliott Key, and Adams Key) and the mainland area at Convoy Point (9 miles east of Homestead) are closed to the public. Biscayne National Underwater Park, Inc., the park's concessioner, has discontinued boat trips and rentals. Park waters remain open for vessel transit only. The closure will remain in effect until further notice," the park announced.

"After suffering severe damage in 1992's Hurricane Andrew, the park implemented a detailed plan for adequately protecting life and property, while at the same time taking into account employee's needs to prepare their own homes and families," officials said. "The plan has been fine-tuned at every approaching storm, and currently calls for preparations to begin at 72 hours before potential landfall. These preparations include shuttering buildings and securing park property."

Dry Tortugas National Park was closed to visitors Saturday. "All licensed commercial transport to the park, including ferry boat and seaplane services, along with visitor services in the park, will be suspended until the passage of the storm," officials said.

On the gulf side of Florida, Desoto National Memorial was to be closed Sunday and Monday at least. "Due to the approach of Tropical Storm Isaac, De Soto National Memorial will be closed Sunday and Monday. The park will re-open on Tuesday if conditions are favorable," officials said.

And at Gulf Islands National Seashore, officials planned to close areas of the seashore, including Fort Pickens, Perdido Key, Fort Barrancas, Naval Live Oaks, Santa Rosa, and Okaloosa, as of 6 p.m. Sunday.

As of 2 p.m. EDT Sunday, the storm was packing 60 mph winds and was located about 50 miles south-southeast of Key West, Florida. It was expected to enter the eastern portion of the Gulf of Mexico on Monday.

A hurricane warning, meaning hurricane-force conditions were expected, was issued Sunday for Dry Tortugas, Florida Bay, and the west coast of Florida from Bonita Beach to Ocean Reef, the National Weather Service said.