As I plunged into the aquamarine waters of the western Pacific, the dark figures swirling below us were thrown into sharper relief. In the depths, dozens of sharks darted through a vast school of mackerel. Closer to the sparkling surface, manta rays feasted on plankton. In the remote Rock Islands of Palau, whipped around by the current, I felt powerless against the ocean’s might. I also felt entirely at peace.

Perched on the edge of Micronesia, Palau is a nation of more than 300 islands that few have heard of and fewer have visited. Settled millennia ago by the peoples of the Malay Archipelago, the 18th century marked the beginning of a series of foreign occupations as Spanish, German, Japanese and American forces variously colonised, occupied and administered the islands before they gained independence in 1994.

Those military powers prized Palau’s strategic location as a staging post between Asia and the Pacific; today, isolation is Palau’s very selling point. To divers like myself, the country represents a lost world, where concerted environmental protection policies have helped preserve a rare fragment of underwater vitality in an ocean struggling to overcome the pressures of commercial fishing and climate change. This pristine and precious realm, now guarded so carefully by its 22,000 inhabitants, is exactly where I wish I were.

As magical as Palau can be on arrival, getting there can be an ordeal. In ordinary times there are flights from Seoul, Manila, Taipei and Guam but seats often book up long in advance, sending ticket prices soaring and making access tricky. When I last visited, in 2019, my lack of foresight forced me to take a circuitous route. Setting off from Laos, I had spent 24 hours hopping through Bangkok, Nagoya and Guam — an itinerary that had seemed outrageous even in a pre-pandemic world.

At each stage, check-in attendants had been bewildered by my destination, with one looking up Palau on Wikipedia to confirm I hadn’t booked a flight to nowhere. It wasn’t until I reached US Customs in Guam that my decision to make the trip had been validated. “There’s nowhere else on earth like it . . . I should never have left,” the officer had said wistfully, recounting his many trips to the islands as a younger man.

For those looking on from afar, it’s easy for Palau to take on a prelapsarian lustre. Adding to that sense in 2020 is the fact the country has yet to record a single case of coronavirus — an achievement made possible both by its remoteness and because the borders were rapidly closed in March, and have remained shut ever since.

A similarly stringent commitment to environmental protection is evident almost as soon as you touch down. In 2017 the country introduced what it billed as a world-first immigration policy: arriving visitors are required to sign the “Palau Pledge”, which is stamped into every passport. As I duly signed my name on the pledge, addressed directly to the children of Palau and promising I would “tread lightly, act kindly and explore mindfully”, I imagined what Bali, my home at the time, might have been like had it followed a similar path.

Marine life was at the top of my agenda, as it is for nearly every other visitor to Palau. My longtime dive buddy arrived the following day after an equally circuitous journey from London, severely jet-lagged but eager to jump right in. At sunrise the next morning, and every day after that, we sped off in an open boat from the marina at Koror, Palau’s largest town. An hour of skipping over gleaming waves and we found ourselves among the Rock Islands, a Unesco World Heritage Site since 2012 and a place of pilgrimage for divers long before that.

Map of Palau

At the edge of Ngemelis Island we arrived at the so-called “Big Drop-off”, a vertical underwater wall that falls for more than 250 metres. Dropping directly off the sheer face, the current dragged me and my fellow divers along a seemingly endless array of soft corals teeming with butterfly fish, parrotfish and hawksbill turtles.

We continued to Ngerukewid, a cluster of 37 forest-covered limestone islands, green humps rising straight from the deep blue like a landscape drawn by Dr Seuss. At the dive site known as “Blue Corner”, we watched sharks feeding on mackerel, to be joined later by swift, silvery barracuda. At the “Blue Holes” — where you dive down into a series of caves within the coral reef — we witnessed the electric sparks of “disco clams” dancing in the darkness.

Then there was Palau’s famed Jellyfish Lake. The inland pool on the island of Eil Malk is home to millions of golden jellyfish that, over tens of thousands of years, have evolved to lose their stings. Snorkellers can now swim safely among them, enjoying the surreal experience of floating beside thousands of pulsating blobs as they undertake their daily migration across the lake in search of sunlight.

Reports in 2017 suggesting tourists’ sunscreen was harming the jellyfish helped to prompt a national ban on sun creams containing certain chemicals that might also be damaging to coral. The prohibited products can be confiscated from arriving tourists, shops selling them can be fined and the same legislation also brought in requirements for tour operators to provide reusable cups and food containers.

That policy built on a series of pioneering environmental protections. In 2009, Palau designated the world’s first “shark sanctuary”, banning all commercial shark fishing in its waters. In 2015, the country introduced legislation to prohibit all fishing and mining in 80 per cent of its waters, with the remaining 20 per cent reserved for local fishermen. The law came into force in January this year, giving this tiny nation (the fourth smallest in terms of population) what is, according to the Stanford Center for Ocean Solutions, the sixth-largest fully protected marine area in the world.

Palau has less natural reefs too. We glided through the ghostly wreck of the Teshio Maru, a Japanese naval supply ship that had been sunk by Allied forces in 1945. Further along the coast, we saw coral fans, octopus and nudibranchs thriving within the fuselage of a Japanese Aichi seaplane.

In stark contrast to Palau’s present tranquility, these sites, and dozens of others, are reminders of the fighting that the islands lived through in the second world war. US commanders thought the 1944 battle for Peleliu, a small island in southern Palau that was home to a Japanese airstrip, would last only four days. In fact, fierce Japanese resistance meant fighting continued for more than two months, with more than 15,000 fatalities on both sides. It became known as “the bitterest battle of the war for the Marines”.

Freediving in JellyFish Lake, home to millions of golden jellyfish that, over tens of thousands of years, have evolved to lose their stings

Having wrested control of the islands from Japan, the US folded Palau into its Trust Territory of the Pacific Islands and its influence continues beyond independence. As part of a 50-year trade-and-defence compact with the US that began in 1994, Washington now sends roughly $15m in annual grants in exchange for “exclusive and unlimited access to Palau’s land and waterways for strategic purposes”. The upshot is that English is widely spoken, supermarket shelves are piled high with American brands, and the dollar is the sole currency.

But other foreign powers have left marks on Palauan life too. In the 18th and 19th centuries, Palau was governed as part of the Spanish Philippines. Today, the ties between the Asian neighbours remain strong, and Filipinos form a sizeable minority on the island, particularly in tourist-facing, English-speaking jobs. German colonialists took over in 1899, seeing Palau as little more than a source of mineral wealth. Even so, their elevation of Koror as the main harbour and commercial centre has persisted to this day. Fittingly, the German Channel dredged through the sand banks and reefs in 1911 to provide a shipping route in and out of Koror now serves as a thoroughfare for the sharks and rays that are Palau’s economic lifeblood.

A Japanese seaplane from the second world war is one of the most intact wrecks in Micronesia, at a depth of 15 metres

Japan, which assumed control in 1920 under the auspices of the League of Nations, left an even stronger imprint. Unlike Spain and Germany, Japan established a comprehensive network of schools, assertively promoting Japanese language and culture. Large numbers of Japanese immigrants moved to Palau and intermarried with locals. The current president, Tommy Remengesau, has some Japanese ancestry as do about 25 per cent of Palauans according to one study. Loan words from Japanese continue to permeate daily life, with bento boxes and udon noodles serving as comfort food to Palauans and Japanese tourists alike.

In the languorous afternoons that followed our daily diving excursions, I wandered around Koror to discover more recent cultural imports. Friendly Bangladeshi shopkeepers staffed convenience stores, while dive shops run by Korean, Japanese and Chinese proprietors competed with American and European ones. A long-running rivalry between an upstairs-downstairs set of hole-in-the-wall Thai restaurants yielded spring rolls and pad thai more flavourful than any I had tasted in London or New York.

There was also The Taj, a curry house with an ocean view that doubles as Palau’s sole nightclub. It quickly became a regular haunt and left little to be desired: the Dubai-trained DJ even obliged as its designated driver, offering weary customers a ride home in his minivan at the end of his set.

Islands have their own way with time. Before I knew it, two weeks had passed in a haze of diving off the outlying islands and multicultural dining in town. But a trip to Palau cannot be considered complete without visiting the hinterland in Babeldaob, the larger and more verdant island across the Japanese-built bridge from Koror. We rented a little Korean hatchback and set off for a loop around the island.

The 200 year-old bai, a meeting house for governing elders, on the island of Babeldaob

Everywhere along Babeldaob’s winding ring road, there are signs of a people striving to keep their culture from washing away. In Airai stood the best-preserved example of a bai, a traditional meeting house for governing elders. Painstakingly restored, the 200 year-old bai’s gables depicted maritime stories from a long-lost Palau. We learnt that after decades of neglect, new bai in traditional designs were now being built across the island to provide spaces for the consensual form of tribal decision-making that to this day coexists with elected government.

In Melekeok, further up the windswept coast, we stumbled upon a conservation site and botanical garden run by volunteers seeking to preserve Palau’s unique flora. Women in this matrilineal society had traditionally been custodians of taro and tapioca patches. Now seeking to rebalance Palauan diets away from sugary American staples, they were tapping into traditional knowledge to preserve the crops and techniques that had fed their people for centuries.

And with most visitors arriving in Palau to dive and do little else, we had many of Palau’s terrestrial wonders to ourselves. In Ngerulmud, the world’s smallest capital city with a population of fewer than 400, we wandered through the government complex without encountering another soul, bar the kindly groundskeeper who gave us a whistle-stop tour of its incongruous Capitol Hill-style buildings. At the northernmost tip of the island, I sat among centuries-old stone monoliths, sea-salt in the air, gazing out on to the Philippine Sea entirely undisturbed.

Palau may have yet to record a single Covid infection, but it has not been unscathed. Addressing the UN General Assembly in September, President Remengesau said the country had experienced “a level of isolation we have not known for many, many years”. Tourism generates more than 40 per cent of GDP, and this year’s shutdown has forced nearly half of private sector workers in to unemployment. Officials are now working to establish a travel bubble with four other Covid-free Pacific states (Nauru, the Marshall Islands, Kiribati and the Federated States of Micronesia), to be connected to low-risk countries beyond the bubble, with quarantine requirements for arriving travellers.

A date for the reopening of borders has yet to be set, but when I do eventually return, even if it is years hence, I need not worry about the islands being changed or despoiled. Even in this most embattled year, President Remengesau used his UN address to stress the need to “repair our relationship” with nature, saying he hoped the country’s decisive action on ocean protection would “inspire ambition elsewhere”. “We are all ocean people, even if we do not live near coasts,” he said.

The president’s own ambitions are rather more modest, if still very much focused on the sea. Following recent elections he will soon retire after a total of 16 years as president and eight as vice-president. “In January I will complete my public service,” he told delegates, “and I will return to being a fisherman in Palau’s pristine waters.”

Follow on Twitter to find out about our latest stories first

Listen to our podcast, Culture Call, where FT editors and special guests discuss life and art in the time of coronavirus. Subscribe on Apple, Spotify, or wherever you listen