Florida Keys Open Water Swim

Founders Park opens directly onto the translucent shallows of Islamorada, where swimmers stroke over sunlit sand rarely deeper than eight feet. Held in April, the Florida Keys Open Water Swim is an open water swimming race in the sea off Islamorada. Established in 2022 by Swim Across America, the gathering brings together open water swimmers of various skill levels to support cancer research and clinical care programs across the region. The event layout gives participants several course options suited to different goals, including distances of half a mile, one mile, and two miles, which correspond to approximately 804, 1,609, and 3,218 metres, alongside a shorter Kids Splash. Swimmers launch into the turquoise sea through a rolling start, spreading the pack comfortably across the calm expanse.

Swimmers are escorted throughout by volunteer kayakers, stand-up paddleboarders, and dedicated angel swimmers who accompany participants along the route, before everyone gathers on shore for the celebratory check presentation to the Miami Cancer Institute. Windley Key originally consisted of two completely separate islands known as the Umbrella Keys.

Race day at Founders Park

The Swim Across America Florida Keys open water swim at Founders Park is billed as its fifth annual edition, held on Saturday 18 April 2026. The Florida Keys Open Water Swim has a two-hour cut-off for finishing. The water volunteers are kayakers, stand-up paddleboarders and power boaters who monitor the swim lane and keep an active eye on all the swimmers. The Florida Keys tourism directory describes Founders Park as a 45-acre community park with a shallow-water beach, an Olympic-size pool, a splash pad, sports courts, playgrounds, a dog park and a marina. The park's beach faces Florida Bay and has tiki huts, picnic tables, cooking grills, a sand volleyball court, playgrounds, outdoor showers and restrooms, according to a local Keys guide.

Florida Bay: drowned limestone basins and mangrove shallows

Florida Bay is an expansive marine estuary that formed between 3,000 and 5,000 years ago when rising post-glacial sea levels flooded the southern reaches of the Everglades. This shallow inland sea is partitioned into more than fifty separate basins, mostly between one and three metres deep, bounded by an intricate maze of mangrove islands and shifting banks of marine mud. These dynamic mud banks are constantly on the move under the wind and tides; the Upper Cross Bank, for instance, steadily erodes on its exposed windward face while accreting new material along its sheltered leeward side. The water conditions across Florida Bay fluctuate dramatically through the seasons, with temperatures in the interior shallows swinging anywhere from 15 to 40 °C (59-104 °F).

Between November and April, thirty to forty distinct cold fronts pass over the region, altering the bay's shallow water column. Because of its fragile hydrology and unique nursery habitats, the International Maritime Organization officially designated Florida Bay as a Particularly Sensitive Sea Area in 2002.

Hen and Chickens and the protected reefs offshore

Today, the Hen and Chickens reef is protected as a dedicated Sanctuary Preservation Area. Further seaward, roughly thirteen kilometres from the race venue, the shallow crest of Alligator Reef sits four nautical miles out from the coast. Beyond the natural reef crest, the surrounding seafloor holds notable artificial dive destinations. About eleven kilometres away, six miles off the shoreline of Lower Matecumbe Key, rests the freighter Eagle Tire Co., which was intentionally scuttled to create an artificial reef in water between 70 and 115 feet deep.

San Pedro Underwater Preserve: the 1733 Spanish treasure wrecks

The shallow channels fronting Islamorada are deeply marked by the wreckage of imperial shipping lines caught in Atlantic storms. The 1733 hurricane scattered shipwrecks over an eighty-mile stretch. The San Pedro is a 287-ton Dutch-built ship that sank during the 1733 disaster while laden with consignments of silver and fine porcelain. Located about fourteen kilometres from the swim site, 1.25 nautical miles south of Indian Key, the resting place is protected as the San Pedro Underwater Archaeological Preserve State Park in eighteen feet of water. Under the calm surface, an eighteenth-century anchor, replica cannons, and original ballast stones encrusted in living coral remain resting on the sand. The San Ignacio lies settled in the reef patch known as Coffins Patch.

Indian Key is located roughly twelve kilometres down the coast from the event grounds. Beginning in the eighteenth century, the island became a thriving forward outpost for Bahamian and Cuban crews who sustained themselves by turtling, commercial fishing, harvesting island timber, and salvaging wrecked cargo from the barrier reefs. In 1840, the military presence expanded across the water when a naval supply depot was constructed on neighbouring Tea Table Key. In 1921, the botanist John Kunkel Small visited Indian Key and catalogued surviving cultivated tropical plants, notably the naturalized sisal agave originally introduced by Henry Perrine. During the colossal 1935 Labor Day hurricane, two operators of the Indian Key Fishing Camp lost their lives when the storm swept the islet.

Hawk Channel: pirate chases and the USS Alligator

The American warship USS Alligator was an active vessel, having previously patrolled the West African coastline between Cape Verde and the equator to interdict the transatlantic slave trade. During that African tour, the schooner's crew had negotiated the acquisition of land around Cape Mesurado on behalf of the American Colonization Society. The USS Alligator captured a pirate schooner near Nuevitas, Cuba, in April 1822. Seven months later, in November 1822, the warship engaged a pirate force forty-five miles east of Matanzas, Cuba, successfully recapturing several merchant vessels that had been seized at sea. On November 19, 1822, while escorting a convoy of merchant vessels through Hawk Channel off the Florida coast, the USS Alligator struck the shallow coral ridge.

After four days of exhausting, unsuccessful efforts to refloat the grounded warship, the crew decided to set fire to the vessel on November 23 to keep it from falling into the hands of pillaging pirates. On Lignumvitae Key, located about twelve kilometres from the race start, the limestone rises nineteen feet above the tides, establishing the highest natural point in the entire Florida Keys. In 1760, Spanish cartographers charted this prominent island as Cayo de la Leña, and by the 1830s, settlers from Indian Key were cultivating plots of sisal across its soil.