"Everything is currently open, and we're running regular park operations," said Park Service spokesperson Joan Amzelmo. "But we're also having a bunch of extra folks in those parks that are assessing the current and future impacts [of the Gulf oil spill] and doing everything they can to prepare, in the event that we have some temporary closures."
Dry Tortugas National Park's coral and sea grass communities are among the most vibrant in the Florida Keys, and sea turtles make their way to its beaches each summer to lay their eggs. (Take a Florida Keys quiz.)
Unlike some other Gulf Coast national parks, Dry Tortugas National Park is not yet visibly affected by the Gulf oil spill.
The parks selected for special monitoring all lie along the U.S. Gulf Coast, which stretches from Texas to Florida. (See a Gulf of Mexico map.) The list could grow depending on how the oil spill's impact area changes, officials say.
"It will depend on what the currents of the Gulf do," the Park Service's Amzelmo said.
As a result of being mostly inland, Big Cypress National Preserve has not yet been affected by the Gulf oil spill.
In addition to alligators, the park's swampy environment is also home to bobcats, black bears, herons, and egrets.
Photograph by Raul Touzon, National Geographic
Everglades National Park
Florida's Everglades National Park encompasses a wide assortment of habitats, including mangrove swamps and marshlands, such as the one pictured above in an undated photo.
So far the Everglades (see Everglades pictures) have suffered no direct impacts from the Gulf oil spill, and remains open to visitors.
The park is the country's longest stretch of undeveloped barrier island—a sandy island that runs parallel to the coast and is backed by a marsh, bay, lagoon, or tidal flat.
According to the latest computer models, large amounts of crude from the Gulf oil spill aren't expected to move far enough westward to impact the seashore, which remains open to visitors, the Park Service says.
However, "if the volume of the spill increases significantly, currents and strong winds could potentially bring remnants of the spill to the Texas coast during the coming months," according to the National Park Service website.
Photograph by Tyrone Turner, National Geographic
De Soto National Memorial
Gulf Coast waters are visible from this lookout point in Florida's De Soto National Memorial, named for Hernando De Soto, the Spanish conquistador who explored much of the state in the early 1500s.
The park, a popular fishing and kayaking spot, remains open and still appears to be unaffected by the Gulf oil spill.
Roughly 80 percent of the park is mangrove swamps, with the rest consisting of pine flatlands and mixed hardwood forests. Serving as nurseries for much of the fish in the Gulf, mangroves are crucial to the region's ecological future—and to the fishing industry.
The park lies directly in the path of the Gulf oil spill, and its Barataria Bay is especially vulnerable, because it's linked to the Gulf of Mexico via waterways, according to the U.S. National Park Service. Upper reaches of that bay are now lined by floating booms, intended to protect the shore from oil.
The park is home to songbirds, as well as swamp rabbits, mink, coyotes, and deer. So far, no animals that live in U.S. national parks have been affected by the Gulf oil spill, the Park Service's Amzelmo said—but that could change.
"To my knowledge, we haven't had [any wildlife affected] on the shores of the national parks," she said. "But we are preparing for that."