Swim with whale sharks in Indonesia's Raja Ampat Islands

Holding a mask and snorkel to my face, I backflip over the side of the zodiac and brush against something large ... really large. Turning around to look, I almost leap right back into the boat, because it's a tailfin the length of my body and it's attached to an enormous polka-dotted whale shark. I'd jumped in beside a traditional bagan fishing platform in Indonesian Papua's majestic Cenderawasih (Bird of Paradise) Bay in the hope of seeing a whale shark, but I scarcely imagined such a speedy close encounter. From the inky depths, another behemoth is sluicing towards me, its metre-wide mouth open, its eye just a blink away from mine. I swim with eight whale sharks in all as they weave around me filter-feeding their miniscule prey among the bait fish jettisoned from the platform.

Cenderawasih Bay is possibly the best place in the world to swim with these gentle giants. In most other locations, such as Western Australia's Ningaloo Reef, whale sharks are temporary visitors following seasonal food sources, which they skim from the surface by ram feeding horizontally. They may be slow swimmers by shark standards, but we flimsy humans have difficulty keeping pace. In Cenderawasih Bay, by comparison, the food is available year-round, so they tend to take up residence and gulp feed vertically in an almost stationary position. They loop around to the platforms again and again ... for their efficient eating and to our viewing pleasure.

This is just one of Coral Expeditions' guided immersive experiences on my 13-night cruise through Indonesia's exotic Spice Islands and biodiverse gems of Raja Ampat and Cenderawasih Bay. Australia's pioneering small-ship expedition cruise line offers an easygoing but thoroughly professional Australian hospitality style as it takes explorers to remote locations with expert guidance on local cultures, fauna and flora. Starting with environmentally sensitive cruises on the Great Barrier Reef almost 40 years ago, the Cairns-based company was among the first Australian cruise lines to offer Raja Ampat itineraries back in 2013. Right on the Equator, this archipelago of about 1500 steep, lush islands straddles 4.6 million hectares (two million of which are Marine Protected Areas). Raja Ampat's location at the crossroads of the Pacific and Indian oceans makes it the bullseye of the Coral Triangle. Today, it's believed that Raja Ampat, together with Cenderawasih Bay and the Fakfak-Kaimana coast, collectively known as Papua's Bird's Head Seascape, contain the richest marine biodiversity on earth.

We're talking a whopping 1700-plus fish species, 600 coral species (three-quarters of the corals found on Earth), five of the seven sea turtle species, 17 species of whales and dolphins, 699 mollusc species, and much more.

Raja Ampat's remoteness is both a boon and an opportunity. A boon because it avoids the damages caused by mass tourism and an opportunity because expedition cruise companies can deliver unparalleled access to a rich array of adventures with plenty of creature comforts.

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Our cruise is an enticing trifecta of Spice Islands' cultural experiences, Raja Ampat marine marvels and Cenderawasih Bay whale shark swims. Along the way, we feast on inspired preparations of delectable seafood, meat, salads and fruit, washed down with Aussie wines and beers. And we feast our minds on tales tall and true told by entertaining expert guest lecturers about the rich diversity not only of coral reefs, tropical fish and birds but also of Indonesia's myriad cultures and voracious conquerors.

Our cruise departs from Darwin and we spend two days crossing the Timor and Arafura Seas, with a stop to plunge directly from the ship into the cobalt, five-kilometre-deep Banda Sea. We're welcomed by kora kora canoes at Banda Neira and get a visceral history lesson into how this tiny speck in the East Indies changed the course of world history, on a guided walk through the township with its mosques and churches, vestiges of Chinese temples, coral buildings, and tropical colonial architecture. First Arabs, then Portuguese, Dutch and English traders (effectively the first multinational companies) jostled for control over the lucrative plantations of nutmeg and cloves, which grew nowhere else in the world. Golden-garbed teenagers perform a nutmeg dance at the brooding Dutch Fort Belgica in the shadow of the simmering Gunung Api volcano. Later, we discover fast-growing staghorn coral and a multitude of fish at its striking lava flow snorkel spot.

Spending a day exploring Misool in southern Raja Ampat, we discover rock art drawings of spinner dolphins and swim in the turquoise Yapap lagoon framed by surreal stone pinnacles. We snorkel and dive at several sites but, sadly, the visibility is poor. This was Coral Expedition's first post-COVID-19 Raja Ampat cruise and none of the crew had been here before. Their knowledge of the best underwater locales will most certainly improve.

On the island of Kofiau we enjoy a boisterous welcome at Kampung Deer, where grass-skirted drummers and flute players escort us around their pretty Christian village, and children sing while their parents help us plant mangroves as part of a Nature Conservancy sustainability initiative.

The limestone-karst-dotted aquamarine seascape at Wayag, in northwestern Raja Ampat, is gobsmacking, especially for those of us who manage the hot and sweaty, root-encrusted climb up Mount Pindito. Wayag also offers better snorkelling and diving with myriad soft and hard corals, turtles, rays and oodles of butterfly, angel, damsel, anemone and parrot fish.

But it's Cenderawasih Bay that steals my heart for here I've come face to face with the world's largest fish in the deep blue sea. If only my smile could be as wide as theirs.

The ship: Coral Expeditions' Coral Adventurer has 60 cabins, carries 120 passengers and is 93.4 metres long.

Get on board: Four extended 18-night Raja Ampat and Spice Islands expeditions (from January to March 2025) have just been released on Coral Geographer, an identical new 60-cabin sister ship. Prices start from $17,590 per person with an early-bird savings of $500 per person for bookings made through 30 April 2023.

Explore more: CoralExpeditions.com

Susan Gough Henly travelled courtesy of Coral Expeditions