South Florida’s rarest luxury: Mansions with dual waterfronts. Any in Miami?

South Florida is a showcase for waterfront wealth, where newly arrived billionaires are snapping up trophy estates along the coast.

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But the rarest properties, according to some South Florida real estate brokers, offers waterfront on both sides of a mansion.

Owners can step out the back door onto a private beach in the backyard and out the front gates to a yacht waiting at a private dock.

That unusual geography is on full display along Hillsboro Mile in Hillsboro Beach, an exclusive stretch of A1A in northeastern Broward County. Of the 47 single-family estates along the Mile, some span the barrier island’s roughly 900-foot width, with the Atlantic Ocean on one side and the Intracoastal Waterway on the other.

Some of the mansions even come with private tunnels running under A1A, allowing residents to reach their docks without emerging to cross the two-lane road.

Real estate agents consider these double-waterfront estates among the rarest forms of residential property in South Florida.

They are possible only in a handful of places where the geography allows a single property on a barrier island to span the narrow strip of land between the two bodies of water. Manalapan and Jupiter Island farther north also have some Atlantic-to-Intracoastal residences.

Hillsboro Beach is just a 3.2-mile-long town with 2,214 residential units, according to the municipality’s 2026 Resident Guide. Besides the 47 mansions, the rest of the town has condominiums and townhomes. The town, established in 1939, has an estimated 2,200-year-round residents, a number that can grow to 3,600 during the winter.

A single, two-lane roadway — A1A Scenic Highway, also known as Hillsboro Mile — runs through the town. The street almost all residential, with one hotel and a private club and no stores or other commercial properties.

The strip has long been known as Millionaire’s Mile. These days, Billionaire’s Mile may be more fitting.

Hillsboro Mile’s formula

So far in 2026, the most expensive residential sale in Broward County was the $42 million July purchase of 1107 Hillsboro Mile by tech and media executive Mason Paul Slaine, according to property records. The 10,101-square-foot estate sits on 1.38 acres.

In May, 1091 Hillsboro Mile sold for $27.75 million. The 1.36-acre, 9,838-square-foot estate also runs ocean-to-Intracoastal and was sold for development. In January, an estate at 1083 Hillsboro Mile sold for $36.45 million. The more than two-acre property has 200 feet of Atlantic frontage and 200 feet along the Intracoastal, plus a separate guest house and dockage.

“We have been pretty much under the radar until recently,” said Hillsboro Beach Mayor Dawn Miller, who also lives on the Hillsboro Mile. She suspects the Atlantic-to Intracoastal geography has something to do with it.

Miller and her family discovered the Hillsboro Mile by accident during the pandemic and moved there from LeGorce Island in Miami Beach.

“It’s a special place to live in. The mile does have a small-town feel. We look out for each other,” she said. “We feel secure.”

And privacy is key. The city’s beach has no public access and cruisers from the town’s police department patrol the mile to closely protect residents. The mayor declined to name well-known residents along the mile.

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Realtors who specialize in selling property on the Mile are also tight-lipped about their clients. Several contacted for this article declined to be interviewed or did not return calls.

But records and social media posts indicate current and past residents include former Miami Dolphins player Zach Thomas; the late Jim Moran of JM Family Enterprises, the late Rick Case and his wife, Rita, owners of Rick Case Automotive Group; and John M. Ferolito, co-founder and chairman of AriZona Beverages.

Most of the well-heeled residents are low-key, not celebrities, the mayor said.

That sense of exclusivity and seclusion is visible from A1A, where a canopied two-lane road runs between the estate homes and beachside condominiums. The town’s best-known landmark is the historic Hillsboro Inlet Lighthouse, visible to boat traffic offshore.

Not just Hillsboro Mile

Hillsboro Mile is not the only place where geography has created this kind of natural luxury.

In Manalapan, a small Palm Beach County town south of Palm Beach and Mar-a-Lago, ocean-to-Intracoastal estates have also become prized holdings.

In June, Oracle co-founder Larry Ellison and WeatherTech founder David MacNeil paid a combined $67 million for a four-acre oceanfront lot at 1960 S. Ocean Blvd. The two billionaires already own the neighboring homes.

Last year, video game billionaire Gabe Newell, co-founder of Valve, paid $70.8 million for a 2.06-acre double waterfront estate. The property includes a roughly 20,000-square-foot house, pool, dock, boat lift and a tunnel connecting the residence to the ocean.

Jupiter Island, farther north in Martin County where golfer Tiger Woods lives, has another concentration of large ocean-to-Intracoastal estates.

Why not in Miami-Dade?

Broward and Palm Beach have the coveted double waterfront properties, but what about Miami-Dade? The county has properties marketed as “double waterfront,” but not by two different bodies of water.

The reason is partly geography — and partly preservation.

In the 1960s, Miami-Dade had a piece of land that might have become one of South Florida’s most extraordinary waterfront estates.

At the southern tip of Key Biscayne, where Biscayne Bay and the Atlantic meet, developers had contemplated ambitious projects for what is now Bill Baggs Cape Florida State Park.

Instead, Bill Baggs, then editor of the Miami News, campaigned in the pages of his newspaper to preserve the land for the enjoyment of the public.

Baggs ultimately helped persuade Elena Santeiro Garcia, widow of Cuban Sen. José Alemán, to sell the property to the state. Florida acquired the land in 1966.

A year late, the property became Bill Baggs Cape Florida State Park, which opened to the public in 1967 and is one of the area’s most beautiful beaches.

Today, what might have become another extraordinary private double waterfront compound is instead public land.

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