Leaning over the railing on the top deck of a five-story ferry, I watch the southern most tips of the two peninsulas that border Tokyo Bay fade into the distance of the gray-blue sea. The gargantuan vessel rocks gently beneath my feet, the steady ocean breeze a comfort on my skin I had almost forgotten existed in the concrete clog of the big city.

I’m just beginning my voyage to Ogasawara, also known as the Bonin Islands. This chain of subtropical islands, 1,000 km from downtown Tokyo, is the most remote region governed by the Metropolitan Government. Formed volcanically, the islands of Ogasawara were never connected to any continent, meaning that competition from outside plants and animals was limited. This has led to independently-evolved ecosystems full of unique species, earning it the appellation Galapagos of Asia.

I head for Ogasawara just slightly over a year since it was officially recognized by UNESCO as natural World Heritage site. Aside from a few islands used by Japan’s Self-Defense Forces, only two islands in the chain are inhabited—Chichijima and Hahajima—with populations of about 2,000 and 500 respectively.

With no airports, the only way to get there is by boat. There are luxury cruises that only stop for a single night, but for those on a budget who want to experience Ogaswara more deeply, the ferry is the way to go. Running from port-side Tokyo to Chichijima about once a week, the voyage takes just over 25 hours straight in good weather.

Although the lengthy travel time and prospect of seasickness continue to deter many, the number of passengers has dramatically increased since induction as a World Heritage site, rising from just under 21,000 in the 12 months before to 31,000 in the year after, more than doubling during peak months. (The number of cruises too has surged, tripling to 12 last year and set to nearly quadruple this year to 47.)

For me the ride is actually quite pleasant and relaxing. I take the ferry second class on Aug. 17, just after the peak Obon season (a nationwide summer break and family reunion holiday). Luckily the sea is calm, the boat hardly swaying at all, and there are only 300 passengers, less than half of capacity, so there’s plenty of space to stretch out in the shared sleeping quarters (even though I’m almost 190 cm tall).

I kill the time on deck reading “Moby Dick” and making friends with other lone travelers. As can be expected, the onboard food is overpriced and lacking in nutrition, but this is more than compensated for by the glorious sunset, a radiant blaze slipping beneath an endless horizon of waves and sky.

Even if the ship had been jam-packed and the weather rough, I would have gladly endured it for the wilderness frontier that is Ogasawara. Of my six nights there, I spend five on Chichijima.

The buildings of the main town are clustered along the shore at the foot of mountains covered in low trees and shrubs — too tropical to be mistaken for anything on Japan’s main island. With souvenir shops, galleries, hotels, restaurants, bars and traditional izakaya (Japanese pubs) lining the well-paved roads, it feels almost like a small resort. There are plenty of accommodations, from cheap dorms (such as Guesthouse Morionoya, ¥2,800/night) to the sumptuous (Hotel Horizon, ¥32,500). I pick Taiyoso, a cozy family-run minshuku in the center of town (¥5,000 with breakfast).

After checking in, I hike up past the local shrine to the top of a small mountain overlooking the town. With light rain falling, toads and snails creep out of the bush, and I get my first sighting of the oka-yadogari, a kind of endemic hermit crab that drags its borrowed seashell around with gristly purple limbs, cute antenna sticking up like pigtails.

The next morning, I walk across a white beach where green sea turtles bury their eggs deep in the sand, washed up shards of dried coral tinkling against each other under my feet like glass wind chimes, the ocean a deep indigo some call “Bonin Blue.” Donning my goggles, I enter a world of pulsating coral, neon fish and mysterious organisms that ripple and swirl vibrantly in the currents. At other beaches, I see a manta ray, a sand tiger shark and a sea snake spotted like a leopard, all of which are harmless if you keep your distance.

Over the next several days, I encounter many more strange and wonderful creatures. During a nighttime tour with senseki guides, or war-site tour guides, I see critically-endangered Bonin fruit bats swoop in on giant wings to hang upside down from a tree like small monkeys, plankton that flicker like fireflies in the surf and bioluminescent mushrooms glowing faintly in a dark forest.

On a motorboat tour to Minamijima Island with the Bamboo Inn, I witness spinner dolphins rising for a breath of air like serrated gears cutting the waves, green sea turtles bobbing lackadaisically to the surface and the fluffy gray forms of hatchling seabirds treasured away in little rock cubbies, before I take a swim with bottlenose dolphins. Whether sea-kayaking, whale-watching or diving, there is so much to see and do that one week is hardly enough, but you have to be careful about costs, as many activities are off limits without a licensed guide due to strict environmental regulations.

There is a good variety of restaurants and bars, serving anything from teishoku (meal sets) to shark burgers, Guinness to sake, although most ingredients are shipped in, making prices fairly high. Island signature dishes include: tempura shikakumame (square bean), a summer veggie that’s crunchy like celery but less fibrous; shimazushi, a kind of white-fish nigiri marinated in spicy soy sauce; and sea turtle, prepared as sashimi or stew. (This turtle is listed by some environmental watchdog groups as endangered, and Ogasawara is the only place in Japan where hunting and consumption is allowed.)

I take a two-hour ferry ride to Hahajima for my final night. At last I find what I was looking for. Quiet, remote, the vegetation is more lush here, the critters more numerous. Restaurants and shops are few; tourists even fewer. I stay at Mamaya, a clean wooden compound serving exquisite home-style Japanese cuisine at a great price (¥4,200/night; add ¥1,800 for breakfast and dinner). I climb Chibusayama and find myself swallowed in a forest of green jags, monstrous tangles of vines, and rows of tako-no-ki (octopus trees), their ramified roots rising above the soil like an octopus standing upright on its tentacles. Gray lizards scuttle constantly across the trail and the green avian figure of Hahajima honeyeaters flit through the branches. The view from the top is breathtaking, a red, purple and green mosaic of trees sloping down to that Bonin Blue.

Talking with the Hahajima Volunteer Association afterwards, I am shocked to learn that Chibusayama has been the target of vandalism. Somebody wantonly broke the branches of numerous endangered trees there and in another area to the south called Minamizaki. Many trunks were also scratched up in Sekimon to the north in a case of trespassing without the required guide. The police are still investigating, but the damage was thought to have been done intentionally by a tourist.

On Aug. 13, the Environment Ministry mentioned the Chibusayama incident when it announced plans to investigate the ecological impact of increased tourism on Japan’s four natural World Heritage sites: Yakushima, Shiretoko, Shirakami and Ogasawara. Sections of Shiretoko have already been closed to the public, and there is discussion of doing the same with the mountains of Yakushima.

Inhabited continuously since 1830, many areas of Ogasawara now marked as World Heritage were developed in the past. Chibusayama, for example, was once used as farmland for cash crops of sugar. While not exactly untouched, the unique ecosystems of Ogasawara have been rejuvenated over decades of hard-fought preservation. Yet having evolved in isolation, they are extremely fragile and sensitive to invasive species that tourists can unknowingly (or purposely) bring. Outsiders like the rat, green anole and planarian worm are already wreaking havoc on indigenous lifeforms.

It is ironic that a U.N. program seeking to protect natural heritage sites may threaten it by attracting tourists. The presence of ecotourists such as myself provides economic incentive for environmental protection, which means everything in our finance-obsessed world, but it also inevitably exerts pressure on the environment. Whether it’s possible to create a new interrelationship in which a large influx of visitors coexists with native organisms in a healthy and flourishing equilibrium is hard to say. But so long as we seek to make nature a spectacle and playground for our personal amusement, this is the challenge we face.

The Ogasawara-Maru ferry runs from Takeshiba in Tokyo to Chichijima approximately once per week. For September, one-way second-class tickets are ¥23,930 for adults, ¥11,970 for children and can be purchased at JTB outlets. For the latest schedules and fares see the website of ferry operator Ogasawara Kaiun: www.ogasawarakaiun.co.jp/english. All other information you need to plan a trip to Ogasawara, including a list of accommodations and activities, can be found on the Ogasawara Village Tourist Association’s website: www.ogasawaramura.com/en/.