If you want to go to a beach to get away from other humans, you'll have to try a lot harder than visiting popular spots like Tulum, Mexico, Saint Barth's or Mykonos in Greece. At the six under-the-radar destinations listed below, you won't know a soul anywhere in a 100-mile radius — and the locals will make you feel like one of their own. Not just that: These untrammeled landscapes are postcard-perfect, free of photo-bombing tourists and full of secret coves just waiting for you to discover them. As icing on the cake, they're all within close proximity to places you may already know and love.

Time's ticking, though. These spots won't stay secret much longer.

You've done Mykonos ... now try Zakynthos

Tired of looking at Mykonos' beautiful windmills? Never. But maybe you're ready to swap out the thumping social scene for something more laid back. Head to the Ionian island of Zakynthos, a little-explored paradise where secret, pearlescent coves are hidden from plain sight by towering limestone bluffs.

The west and north sides of the island are the quietest and most beautiful — and the latter is where you'll find the stonewalled Porto Zante Villas and Spa, which Greece expert Mina Agnos, president of Travelive, says offers an unsurpassed experience. "Each villa has panoramic views, a private heated swimming pool, and access to a private section of beach," she said. Other island draws: the neon-blue Shipwreck Beach (named for a destroyed vessel that still sits on the sand), endangered Caretta Caretta (loggerhead) sea turtles, and plenty of yacht charters for a day of Ionian beach-hopping.

You've done Saint Barth ... now try Sint Eustatius

Not every place that Christopher Columbus discovered was put on the global map. Case in point: Sint Eustatius, one of the most under-the-radar islands in the resort-rich Caribbean, which the famed explorer first documented in 1493. Little has been said about it since then. Its sole city, Oranjestad, is known as the "smallest capital in the world," and the entire island has a population of just 3,183.

But Statia, as it's known, is just a short puddle-hopper flight from Sint Maarten, and scuba diving expert Robert Becker, of ProTravel, considers it one of his all-time favorite places. "There's no mega-tourism, and most people don't even know it's there," he said. "It's got great hiking and lots of gorgeous tropical foliage, plus very welcoming people who have a genuine desire to know that you're enjoying your stay." Bunk up at the Dutch colonial-style Old Gin House, where Becker says you'll feel like you're staying with family friends, and pack goggles: The island is ringed by a national marine park, with impeccably protected coral reefs and tropical fish stocks.

You've done Punta del Este, Uruguay ... now try Mancora, Peru

"This beach is popular with locals, but few Western visitors have discovered it," said Ashish Sanghrajka, Latin America enthusiast and president of Big Five Tours. That's because most travelers to Peru head inland to the Sacred Valley, rather than up the coast. That's a big mistake.

Not only does Sanghrajka say that the beach town of Mancora — close to the border of Ecuador and a four-hour flight from Lima — has "some of the best banana board surfing in Latin America." It's also home to a stunning nine-room resort, Kichic. Nearby, at Túcume, you can still accomplish some of that requisite Peruvian ruin-spotting; the adobe complex is nearly 1,000 years old. And soon enough, the country's luxury resort standard setter, Inkaterra, will open a beach retreat in the vicinity — in a fishing town that inspired Ernest Hemingway's "The Old Man and the Sea."

You've done Ibiza ... now try coastal Portugal

Portugal's tourism mojo has skyrocketed in the past year, luring many to its romantic cities and dreamy wine valleys, but its rugged beaches have yet to experience the boom. According to Virginia Irurita, who specializes in custom trips to the Iberian peninsula, there "are no unexplored beaches left in Spain," but several spots along the Portuguese coast are still "wild, beautiful and empty." Take Odeceixe: It's set at the juncture of the Atlantic and the tightly coiled Ceixe River, which separates the Algarve from Alentejo.

There, you'll find pristine beaches between the river's curled banks as well as on the quartz-lined ocean coast — so many of them that you can kayak from one to the next, looking for resident otters or places to avoid human contact. The crowds are thin, in part because there are no luxury hotels. One exception: Herdade do Touril, an affordable boutique bolt-hole with direct beach access. It's far more stylish and hospitable than its 100-euro-per-night price would let on.

You've done Zanzibar ... now try Likoma Island, Malawi

Alex Malcolm, founder and managing director of Jacada Travel, says off-the-beaten-path Likoma Island on Lake Malawi "should be considered a 'world's-best beach,' " both for its "current-free, crystal-clear waters" and its vibrant cultural draws: The island is dotted with fishing villages.

Stay at Kaya Mawa Resort, he told us, where "each room was individually designed in partnership with a local workshop set up to empower single mothers, and the whole staff comes from neighboring villages," for a mix of social consciousness, authenticity and intimacy. How to get there? Fly to Johannesburg first, then onto Lilongwe, Malawi, where a light aircraft can take you to Likoma Island. It's a hike — but worth the commitment.