Natal, Brazil

Bring the heat: So your globe-trotting friends have Brazil-beach-hopped from Salvador, Bahía, all the way south to Florianópolis, but we bet none have been to the northerly city of Natal. Imagine a sea of sculptured sand dunes that push up against the perfect blue waters of the Atlantic—the juxtaposition is fantastic. Take a thrill ride on the dunes (pictured) with one of the region's lunatic buggy drivers before diving in the warm sea among the black dolphins. And expect an all-nighter in the town's ready-for-anything Alto de Ponta Negra neighborhood.
Select sand: The sexy crowd hangs out at Morro do Careca, where you'll find fine bodies working up a thirst playing beach soccer and volleyball, and then quenching it with ice-cold Brahma beers while chilling under yellow umbrellas.
Hookup potential: Through the roof. When you're wondering if you should invite along a romantic interest on your trip to Brazil, first consider the local saying, "Why bring sand to the beach?" Natal, with a population of around a million people, doesn't see a lot of tourists, so chances are the trim, black-haired surfer dudes and dark-skinned, white-teethed garotas in tiny bikinis will be very pleased to show you around.
Privacy rating: 1. This scene is all about showing off.
Pillow talk: Natal can be a bit rough around the edges, so go for the service and comfort of the Pestana Natal, which has three pools just off the beach and a staff that mostly speaks English. It's also where you can hire a dune-buggy driver who's less maluco ("insane") than most.

Gotland, Sweden

Bring the heat: The funny thing about Stockholm is that when it finally gets warm, all the Swedes leave. They make for their summer homes on the thousands of islands that dot the Baltic Sea between Sweden and Finland. There they roast in saunas, sit by the shores of lakes and the Baltic, and drink bottomless bottles of aquavit. If you think the Swedes are good-looking people, and you would like to get to know them and their mating rituals better, get thee to the thousands of islands in the Åland Archipelago.
Select Sand: Gotland is the biggest island in the north Baltic Sea, drawing ruddy-cheeked visitors from around Sweden. The countryside is a riot of greenery, and as the sun never sets in the summer, you can spend as much time as you like on the miles of empty beaches.
Hookup potential: What's the Swedish phrase for "sure thing"? The society is quite permissive, and Midsummer's Eve is the biggest (and longest) party day of the year.
Privacy rating: 10. The Åland Archipelago is packed with 6,500-plus islands.
Pillow talk: While the medieval town of Visby is the place to go out at night, better to base yourself in Gotland's countryside. Hotel Toftagården is close to the water, has its own sauna (an important thing to the Swedes), and has both cute little private cabins and traditional hotel rooms to choose from.

St. Philip, Barbados

Bring the heat: It's only 21 miles long, yet Barbados has a bit of everything: Fine dining and bawdy beach shacks, cricket matches and Mount Gay Rum tours, the posh Caribbean Platinum Coast and the rough-and-tumble (and Highland-like) Scotland District up north. Gauge your partner's whims and go.
Select sands: Been fantasizing about pink-sand beaches while sitting in your beige work cubicle? Imagine waking up, running out of the hotel with your lover, and straight onto Crane Beach, backed by tall cliffs and baby powder–fine sands that glow pink. It's a primal place that might encourage a detour back to the hotel.
Hookup potential: Minimal. There are other tourists to check out, but Barbados is really about spiriting out of town for a week with somebody you'd like to know better.
Privacy rating: 8.3. The western coast packs 'em in, leaving your side of the island just as it should be: empty.
Pillow talk: Unless you're desperate to hang around the crowds, the Crane's remote location—on an east-coast cliff overlooking Crane Beach—is ideal for intimacy. You have a choice between the rooms in the original section (built in 1887) or the new private residences, which come with private plunge pools.

Perth, Australia

Bring the heat: The Aussies may be world-class friendly, but even they get tourist-weary in places like Sydney. To achieve that "I'm an outsider, wanna buy me a drink?" sizzle, it's hard to beat the west coast, near Perth. The locals pride themselves on being a little wilder, a little more independent, and a lot more entertaining. Challenge a cute one to a drinking contest.
Select sand: This photo was shot at Mindarie Keys—a perfect spot on the 20-plus miles of Sunset Coast that run north from Perth. Think long washes of bone-white beaches and a clear Indian Ocean that blushes brilliant red at sunset. If you set off from Perth's busy city center, you'll be here in less than 30 minutes.
Hookup potential: Great-looking locals. Lots of them. You're the one with the accent. Do the math.
Privacy rating: 7.7. Chances are, new acquaintances will love to show you their favorite swath of solitary sand. If you're in the mood to duck away on dry land, ask for a tour of nearby Yanchep National Park, famous for some 600 natural caves and colonies of fuzzy-wuzzy koalas.
Pillow talk: Perth's a lovely city, but there's no reason to listen to the sound of traffic when you wake in the morning. Opt instead for the sound of boats clinking softly together at the Mindarie Marina, which has really nice suites at even nicer rates. Each has a balcony overlooking the water and access to the swimming pool and tennis courts, and—most importantly—the hotel is about a three-minute walk to the beach where this lass was photographed.

St. Lucia, Caribbean

Bring the heat: If curious couples once fantasized about Jamaica—a sensual green-and-blue paradise that's still close to home—these days St. Lucia has assumed that role. The verdant island has an increasing number of top-tier properties, a host of possible land and water adventures to spice things up, and plenty of sand to roll around in as the surf breaks over your bodies.
Select sand: The island has archetypal Caribbean beaches such as Reduit—which, while oh so pretty, are sardined with sun-reddened tourists. If lying around doesn't suit, Cas-en-Bas on the Atlantic coast is more geared towards the adrenaline set, with pursuits such as kiteboarding or racing in the surf on horseback, like the handsome fellow pictured. You can rent horses from the International Riding Stables in nearby Gros Islet (though we'd suggest springing for the saddle rental, too, unlike this guy).
Hookup potential: If all that sunshine, good food, and beautiful scenery doesn't help your game…well, there's always the priesthood.
Privacy rating: 6.5. The island keeps getting more popular, so ditch the crowds and slip away to a hidden spot—underneath the waterfall at the Botanical Garden's mineral baths, for instance.
Pillow talk: The newest resort property is Landings St. Lucia, in the north (only 15 minutes or so from Cas-en-Bas). The one- to three-bedroom villas are sparkling new, there's an 800-foot private beach dotted with pools and hot tubs, and the huge RockResorts spa will get the kinks out.

Oahu, Hawaii

Bring the heat: Oahu gets its share of loud shirt–wearing tourists, but it's surprising how few venture around the entire island, choosing instead to nurse fruity drinks in Waikiki. Which leaves the North Shore and nearby beaches to the hot surfer boys and girls and superfit locals. And you're free to mix it up with them.
Select sand: In winter, the North Shore's Sunset Beach is legendarily sexy—have you ever seen so many hard bodies toting around their surfboards? Great ogling, but you don't want to get in that pounding surf yourself. A short drive away is Kailua Beach, a sweet arc of sand where the pretty girls and sporty guys from the moneyed enclave of Kailua like to body-board.
Hookup potential: Score! Oahu is a no-shirt, no-shoes, no-problem island. Mix in all the athletic types who travel here for the swells, the young military people stationed here, and the happy-go-lucky locals, and you get sparks.
Privacy: 2. Sorry, bud, it's a small island, and the locals have claimed the most secluded bits as their own.
Pillow talk: Turtle Bay is right at the North Shore—and after a long evening hanging out at the house where all the surfers live, you won't want to drive all the way south to one of the big resorts. If possible, book one of the 42 cottages, which have more personality than the 400-plus rooms.

Lanzarote, Canary Islands

Bring the heat: Looking for heat, you say? Well, this is a volcanic island, after all, and despite Lanzarote's location 100 miles off the coast of Africa, it's Spanish (and the locals are, well, passionate). Much of the interior is made up of jagged lava fields, and the black sand beach pictured here is called El Golfo.
Select sand: If quiet splendor (and skin) is your thing, head south: Caleta del Congrio is a remote beach at the island's southern tip where fair young things are known to shed all their clothes. Choices abound, though: The island is ringed by some 90 white-, golden-, and black-sand beaches.
Hookup potential: You'll find a steady flow of tourists, from Spain and beyond, chasing a fun weekend in the sun. For those who like surfer types, make for the north of the island and the wild, four-mile-long Famara Beach, where board-lovers do their thing.
Privacy rating: 8.7. We already said it: 90 beaches.
Pillow talk: The influx of budget vacationers hurts the lodging around the island, but the Hesperia Lanzarote, which has sister hotels in Madrid and Bilbao, gets it right. Located in Puerto Calero, it has 46 suites and 289 standard rooms; four swimming pools; comfortable cabanas on the water; and a good, clean design that plays up the Mediterranean influence.