From the port-side window of the 19-seat passenger plane, the island of Niijima, 100 miles southeast of Tokyo, looked like any other tropical paradise. There were volcanic mountaintops wreathed in white clouds, valleys of verdant green jungle, and beaches filled with sand so bright and white the whole coastline looked as if it had been sketched out in chalk.But as seat belt lights flashed, tray tables went up and the captain arced the plane toward the landing strip, the postcard-perfect scene dissolved and a distinctly industrial landscape came into view. What I thought, or imagined, was a quaint, thatch-roof village was instead a shabby-looking fishing port. We rode into Honson, Niijima’s main town, in a shuttle van to find that the stores were all closed and the streets empty. It felt less as if we’d landed on Fantasy Island and more like the Twilight Zone.Niijima, one of nine inhabited islands in Japan’s Izu archipelago, has been a place of many faces. Around the 18th century, during Japan’s Edo period, it served as an island prison for mainland exiles. By the 1960s, the Japanese defense department moved in and shot rockets and missiles from its coasts. For the past few decades, it has been a weekend escape hatch for harried city residents and college students looking for sun-drenched island life a 40-minute flight from Tokyo.More recently, Niijima has become one of Japan’s top surfing destinations. In the summer months, Habushi-ura, a stunning stretch of Windex-blue water along the island’s west coast, has some of the best surf in all of Japan and is host to a number of international surfing competitions. A handful of young Tokyo surfers have since made Niijima their year-round home and created a burgeoning surf scene.But getting around Niijima, I was warned, was not easy. Few locals spoke English. On some weekends the island was so crowded with college students that it was impossible to get a room. At other times, it resembled a ghost town where even the basics — eating, drinking, sleeping — could be a hassle. In its heyday in the 1980s, there were more than 240 places to stay on the island; now there are only 30.We checked into Minshuku Hamasho, a simple Japanese bed-and-breakfast, and set out at twilight to find dinner in Honson. While the town itself is small — only 10 or so blocks — the streets are narrow and dark and restaurants have no signs and no addresses and offer no indication that they are open, or even exist. (A menu on the wall outside? Forget it.) The way to find them, we discovered, was to walk quietly in the middle of the empty streets and listen for clues: a muffled conversation, a clink of plates, the creaking hinge of a quickly opened door.The next day we moved on to Saro, a guesthouse about three blocks north in central Honson. Run by a young couple from Tokyo, Saro, with its warm wood finishes, soft ambient lighting and vintage bossa nova music playing softly from corner speakers, offers a splash of hip and stylish civility to an otherwise unremarkable neighborhood. The host, Shotaro Murakami, a 26-year-old who grew up on Japan’s southern islands, met us in the lobby and led us upstairs along a low-ceilinged hallway to our room, whose furnishings consisted entirely of a tatami mat, a futon and a tiny tea table — all the necessities. That afternoon it was time to explore the island, coast to coast. At just 7 miles long and 1 1/2 miles wide, Niijima is too small to bother renting a car and too big to comfortably explore on foot — in other words, a perfect place to ride a bike. We rode our beat-up beach cruisers toward Habushi-ura, Niijima’s world-famous surfing beach. With its vast parking lot and concrete steps leading to the water, Habushi-ura wasn’t quite the tropical beach paradise we had expected, but it did have a kind of postmodern charm. Because the waves were so small, we bodysurfed instead of renting surfboards and then got back on the bikes and headed west.A two-minute ride from Habushi-ura was Surf Station Habushi, the center of Niijima’s surf scene. This hotel, restaurant and surf shop offers board rentals, wet suits and whatever else is required to catch some waves. The rooms are simple with short beds, bare walls and sailboat-size kitchens, but perfectly clean and functional, and the dining area was filled with young, surf-obsessed guests.A four-minute ride up the road led to Habushi-ura Camp-jo, a spectacular camp spot in the shadow of Mount Miyatsuka, with spacious sites, hot showers and a sheltered cooking area. All campsites are free year-round and, in the summer months, are the scene of rowdy parties.That night, after an extraordinary meal at Saro that included no fewer than 12 meticulously prepared dishes, we headed out to a twice-weekly beach party on Mae-hama beach, a five-minute walk from town. Every summer, a crew of disc jockeys from Tokyo named Wax sets up a sprawling encampment of plywood shacks, stages and a full bar on the sand a few hundred feet from the water’s edge. Saturday nights are reserved for electronic dance music, but on Wednesday, the night we were there, Wax hosted a reggae-style event called Habushi Man Vibration!, which the fliers described as “Original New Island Beach Partyup,” but we were exhausted and headed back to Saro for some sleep.The following day, our last, we pedaled south to take in some of Niijima’s cultural attractions. The first stop was Yunohama Onsen, a free public hot spring located cliffside beneath the Doric arches of a faux-Greek ruin. For all of its kooky Las Vegas-ness, it’s a stunning place for a dip, especially at night when the pools glow with multicolored lights.A bit farther south was Niijima Glass Art Center. With its hangar roof and multiple-story staircase that leads to an observation deck, the center is an interesting piece of design in its own right. The distinct, green-colored glass produced here is made from locally mined Koga stone, found in only two places in the world, Niijima and Lipari Island, Italy. The artist Dale Chihuly came here in the late 1980s and based his 1991 work Niijima Floats on the local glass and glassblowing techniques. When we were there, the glass artists welcomed us into their studio to watch as they fired vases — a fascinating, if suffocatingly hot, experience.That next afternoon, a few hours before catching the ferry back to Tokyo, we rode out to the beach for one last swim. It was there, free-diving with masks and snorkels along Mae-hama, that Niijima’s many contrasting faces came most clearly into view: on one end of the beach was an imposing concrete sea wall; on the other, an Eden of white-sand beach and wild blue water, where below us was a spectacular assortment of vivid sea life. Beauty on this tropical island, we realized, just depends on which direction you happen to be looking, and it’s not always obvious: it’s hidden beneath the surface, behind closed doors and under the cloak of night.