Swim with whale sharks in this impossibly stunning part of the world

The night sky has barely lifted as the world's biggest fish - a whale shark - brushes against me in Saleh Bay, Indonesia. Its tie-dyed-patterned skin is surprisingly smooth, velvety against my skin. She slowly opens her metre-wide mouth, vacuums up thousands of krill then graciously glides away. At six metres long and a juvenile she's four times my body length, but as a filter feeder, eating plankton and tiny fish, and unable to swallow anything larger than a grape, this gentle ocean giant poses no threat. Two more whale sharks join it, and I'm lost to their world. Early morning sunbeams fan out through the water, illuminating their swaying torsos as they drift, twirling and twisting - premier dancers of the ocean. Two hours flash by before they disappear into deeper waters.

I'm on an eight-day voyage with intrepid small-ship cruising company, SeaTrek Sailing Adventures. Passionate about marine conservation they pay local fishermen a healthy spotter's fee to locate whale sharks. Because their fins fetch depressingly high premiums they are constantly under threat. By educating locals on how integral whale sharks are to marine health, these fishermen now protect them.

Back on the Ombak Putih (White Wave) - our 12-cabin 24-berth Indonesian phinisi schooner, which we boarded in Amed, East Bali, two days earlier - a singsong of chatter continues. The morning's nervousness at swimming with fish that can weigh up to 20 tonnes and reach nearly 10 metres in length, is replaced with sated smiles. "They were incredible, unforgettable - one came so close, we were face to face," Amanda from Melbourne says. There's a diverse mix of characters on board: specialist doctor, accountant turned cleaner, maintenance engineer, dressmaker to the stars, bathroom outfitter, retirees and an indigenous education coordinator. Add an artist who sculpts clay into male and female genitalia and lively conversations flow as we set sail indulging in a king-sized breakfast. We next drop anchor at Sangeang Island, a small volcanic landmass in the Flores Sea.

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The island is home to Bontoh Village and, as with each experience, we go ashore in inflatable dinghies. Hot black volcanic sand quickly reminds us we're in mother nature's hands as Sangeang Api mountain puffs overhead. Most villagers have been evacuated due to volcanic activity. A few dozen remain, tending livestock, helping Buginese boatbuilders who rent land to construct colossal 350-tonne schooners, much like the live-aboard boat we're sailing on. The Buginese use boatbuilding traditions passed down through generations. Without blueprints or drawings, it's a knowledge learned by hand using minimum tools. Men run up and down thin planks reaching a 40-metre hull; site safety doesn't exist. Below, women weave colourful handwoven scarves to sell to occasional visitors.

It's a free-range existence. Goats, buffalos and chickens roam the shore while young children treat the island as their playground, their teacher in nature. There are no first-world amenities; it's a tenuous lifestyle, one that could disappear under ash, without warning. But life ticks away in harmony in an unmaterialistic world where their main commodity is each other.

We wave goodbye, bouncing across the ocean, back to cold towels, freshly made juices and banana fritters coated in chocolate. Sailing onwards, we pass low-lying islands petticoated by frilly beaches. Some guests retreat for siesta, others lounge on the upper deck watching sundrenched archipelagos go by. Cut off from the outside world there's nothing we need. It's library quiet and we dissolve into downtime comforts.

Three blissful hours later we drop anchor at Gili Banta Island, the afternoon's snorkelling arena. From the beach we flipper metres out to an exquisite aquarium of rich coral, sea sponges and seagrass, and a kaleidoscope of impossibly bright colours. Yellow butterfly fish, pink anthias and clown fish flit around corals covered in rope-like tentacles, tunicates, and worms called feather duster and Christmas tree. Zoom in, you'll see nudibranchs (sea slugs) glowing in iridescent hues; zoom out, the wide-screen of tropical sea life will hypnotise you as the world above is tuned out. Tune in, you'll hear crackling - it's fish "talking".

"It's like swimming in a jewellery box!" Tamsin from Melbourne says as we stretch out afterwards on silky sand. In late afternoon light, the tireless crew prepare a beach barbecue. Under fairy lights wrapped around parasols we enjoy grilled shrimps, black chicken (an Asian delicacy), vegetable skewers, beef satay and tropical fruits. Guitars are strung, Indonesian songs are sung and we dance under stars, throwing inhibitions to the gentle breeze.

Our days are filled with cultural excursions and we share experiences over delicious dinners as we sail through the night. Talks given by our knowledgeable guides, Anastasia and Narto, educate us on tribes, marine life and the venomous Komodo dragon - the planet's largest lizard, and the following morning's (and our final day's) adventure.

The rules are set on entering Rinca Island, Komodo National Park. Stay in line. Komodo dragons can see movement 300 metres away, smell scents to eight kilometres and run 18kmh. Guards carry pronged sticks to ward them off. "To become an adult Komodo dragon is a difficult life. Because they're cannibals, they eat their babies - it's natural selection," the ranger says as one appears. Stealthily he clambers towards us, one claw after the other, increasing speed. His tongue flicks the forest floor, foraging for food. He snakes closer, his armoured scales swaying from side to side until the ranger gently pushes him back.

We trek on, passing buffalos, monkeys and deer as we climb a steep hill. At its peak, a panorama of islands hedged by turquoise-hued ocean lies before us. Anchored in the distance, the Ombak Putih looks majestic, like a warrior ship. Her masts gleam, flickering sunlight as though she's calling us home to farewell people who have become fast friends on a trip of a lifetime. And, like the whole voyage, I know it will be a night to remember.

Getting there: Jetstar Airways, Qantas and Virgin Australia fly direct to Denpasar, Bali, from most Australian cities. Lion Air flies to domestic destinations where some SeaTrek cruises depart from.

Cruising there: SeaTrek Sailing Adventures offer a range of cruises. The writer took the Whale Sharks, Corals and Dragons trip, which starts from $US5200 ($8100) a person, including meals, park entries, excursions and snorkelling equipment.

Explore more: seatrekbali.com

The writer was a guest of SeaTrek.