A thunderclap of flapping wings made me slam on my brakes, skidding my bike tires in the sand. In a small clearing, not one but two bald eagles, startled by my approach, were taking flight right in front of me. They hovered just above my head before catching the stiff offshore breeze.

It was my closest encounter to date with our national symbol in the wild — but this wasn't my usual eagle-spotting territory on the Mississippi River or Lake Superior. This was the tropical Gulf of Mexico, and I was in Florida, immersed in the palm trees, beaches and wildlife on the remote island of Cayo Costa, some 25 miles west of Fort Myers.

I poked out of the woods onto a deserted beach on the leeward end of the isle. Floating brown pelicans were enjoying protection from the wind, but no one else was around. This wasn't just "Old Florida"; this was Florida before Ponce de Leon even named it Florida.

A spot on my map labeled "Quarantine Rocks" marked this beach as a circa-1900 military quarantine for incoming foreign ships. Seafarers once had to stop here and be tested for malaria and yellow fever — and perhaps submit to a longer stay. The only trace I could find was some weathered old posts embedded in the sand. Just a few weeks after my trip one year ago, the word "quarantine" would become a little more personal for all of us. Thinking back, that wild paradise on Cayo Costa felt like a better place to hide away from disease than, say, a snowed-in duplex Up North.

The local tourism industry seems to know it. Last fall the Beaches of Fort Myers and Sanibel aired a series of TV commercials in the Midwest with romantic, spacious imagery I recognized from the trip. This winter, when leisure travel is discouraged, Minnesotans who do find themselves in Lee County, Fla., could do a lot worse than escaping the crowds on Cayo Costa.

There has long been a wide pipeline between Minnesota and Fort Myers, with upward of 10 nonstop flights arriving every day, even now. The Twins are kicking off their 31st spring training at the city's Hammond Stadium, with limited spectators. Baseball or not, visitors landing at Southwest Florida International Airport will first want to beeline to one of the coastal island communities of Fort Myers Beach and Sanibel.

Last winter, downtown Fort Myers Beach was a riot of swimsuit shops, seafood palaces, open-air bars, rooftop brunches and bumper-to-bumper traffic on the sole two-lane drag. Surfside resorts blasted reggae and country music and a few college bros played beach games, but most of the sandy real estate was packed with tanned and burned baby boomers who most definitely seemed to be doing OK. Wasting away in margaritaville was all well and good for a day or three — but even back when the coronavirus pandemic was still a rumor, I wanted to find a more natural, unpopulated side of southwest Florida.

Key by the coast

I was staying in Fort Myers Beach as a guest of my girlfriend Sabrina's family, who has been escaping there annually for three decades. At the rental-car counter, my eyes skimmed the tourist map and landed on an unnamed island in the upper left corner, in a remote archipelago that might well have been labeled "Here Be Dragons" — or, at least, "Here Be Dolphins." That island is Cayo Costa ("key by the coast," pronounced in flat English: kay-oh cost-ah), and it's one of Florida's least-visited state parks since it's only accessible by boat.

One morning I corralled Sabrina and her mom, Sharon, for a day trip to the park. Our journey began with a one-hour island-hopping drive: across the causeway to green, exclusive Sanibel Island, with its whopping $6 toll. A coyote darted across the road; they've been on Sanibel since 2011.

The next bridge leads to even more prestigious Captiva Island, full of immaculately groomed estates and five-star resorts. This is the end of the line for cars, where we checked in at Captiva Cruises for a 12-mile boat ride. The day trip is billed as a "shelling cruise," and Cayo Costa itself is barely mentioned on the booking site. I was bemused by the shelling emphasis, but drawn in by the prospect of a bikeable island with 9 miles of unspoiled beaches. Passengers are instructed to bring all the food, water and supplies they'll need for the day.

High winds that day kept small craft docked, but our motorized catamaran, Santiva, set off into the shallow green waters of Pine Island Sound with about 40 passengers, including some who would be sailing on to the island village of Boca Grande. Mile-marker posts in the sound were crowned with osprey nests. A pod of pelicans dove violently at the water, hunting for fish. Tour guide Richard Finkel talked serenely about the sights.

Hurricanes in the 1920s tore narrow Captiva Island in half, creating a separate North Captiva. The north side hosts an off-the-grid community of 300 homes, reliant on generator power and golf carts. "Definitely a different way of life," Richard said. We passed between two more unique inhabited isles: quiet Cabbage Key, a Jimmy Buffett hangout said to have inspired the singer's yacht-rock hit "Cheeseburger in Paradise"; and Useppa Island, an Old Florida throwback with high-end resorts dating to the 19th century.

As Santiva docked at Cayo Costa, Richard spotted our first bald eagle soaring above the tree line. Everyone boarded a free tram to the gulf side, but it pulled away without me. I rented a rusty beach cruiser and purchased some $10 bug spray (which I wouldn't need in the wind) from the small park store, and took off down the sand road. A tunnel of palms and pines opened up to a gorgeous scrub landscape with a few cactuses, under a blinding blue sky.

When I arrived at the gulf, Sabrina and Sharon were already two specks on the wide, white-sand beach. A whipping red flag signified "high surf and/or strong currents," one level below "water closed to public." In the swooning heat I momentarily felt transported to a beach I'd visited in Puerto Rico.

I decided to bike roughly clockwise around the northern half of the island. Just off the beach, families occupied a handful of rustic, stilted camping cabins. A mile later, I had my close encounter with the two eagles. In that clearing I found a headless silver kingfish on the ground; I had interrupted their lunch.

My two-hour ride also stopped under Spanish moss, amid coastal scrub and along the boundary of a mangrove swamp. A brown juvenile ibis let me follow it for 50 yards before scurrying into the woods. I reunited with Sabrina and Sharon, whose shelling finds included a perfect sand dollar. They had also spotted two dolphins, skimming the surface of the gulf.

I had one last order of business after the vigorous ride: to jump in the water, red flag or not. Trusting in my swimming ability, I plunged into an immediate drop-off near high tide, communing with the vast, green gulf. On our cruise back to civilization (and to a fine grouper sandwich at Captiva's outdoor Key Lime Cafe), our guide Richard pointed out a row of historic fishing houses, standing high above the water on stilts. He surveyed the broad Pine Island Sound around us, devoid of Florida sprawl.

"When you look around here, 360 degrees, you don't see the high-rises like you would elsewhere in the state," the native New Yorker reflected, summing up the appeal of the place. "It really puts you in a different frame of mind."

Quiet side of Sanibel

Sabrina and I just couldn't return yet to the land of ice shanties and snow emergencies. Fortunately, a one-hour tarmac delay we had suffered upon our arrival, and our ensuing online complaints to Frontier Airlines, resulted in $175 in vouchers — virtually enough to cover new tickets home two days later than planned.

I booked a nature tour with Seaside Kayaking out of Bonita Springs. Justin Finley, a lifelong resident, led three paddlers through the fascinating mangrove swamps of Estero Bay. I got up close and personal with tricolored herons, pelicans and ibis. We explored an oyster reef and tracked a gorgeous, flamingo-like roseate spoonbill. Justin brilliantly explained the ins and outs of the mangrove ecosystem, though I couldn't overlook the condos and hotels on the horizon that had been absent on the Cayo Costa cruise.

Later on Sanibel Island, we joined a nature and sealife cruise with Tarpon Bay Explorers, a big ecotour operation serving the popular J.N. Ding Darling Wildlife Refuge. Naturalist Mandy Hunt confessed that there's little rhyme or reason to dolphin sightings. But the eagle-eyed guide did spot a vacationing common loon, decked out in its darker winter plumage. Yet more evidence of that Minnesota connection.

For our last night, we lucked into a last-minute cancellation at Tropical Winds Beachfront Motel and Cottages, by far the cheapest lodging we could find on Sanibel. The row of classic beach cottages was a short walk over a grassy dune field to the pristine beach on the island's much less developed west side. We strolled the endless beach at dusk, while scattered visitors were shelling. We peered at live clams opening and closing their shells. It was here where my bug spray would have come in handy, though, as we both brought home itchy bites from the fabled "no-see-ums."

I took one last dip in the gulf as the best sunset of the week plummeted into the blue-green horizon. That was followed by the rise of a peaking full moon, which bathed the wild shore in an ethereal glow.

Simon Peter Groebner Instagram: @simonpeter6

Cayo Costa State Park

Where: 12 miles north of Captiva, Fla.

Admission: $2. Tent camping $22 per night; primitive cabins $40 per night (floridastateparks.org/CayoCosta).

Getting there: The island is reachable only by boat. Captiva Cruises offers full-day "shelling" trips to the park Wednesdays and some Thursdays ($55) and half-day trips Mon.-Sat. ($45; captivacruises.com).