The few scraps I glean about Fiji's 57 Lau islands, before cruising among them, come from travel writer Paul Theroux. In The Happy Isles of Oceania, Theroux describes the Lau group as "one of the pretty little star-clusters in the universe of Oceania".

"There is a strong Tongan influence in the Lau culture," Theroux writes of the string of islands dangling to the far east of Viti Levu. "They wear crunchy mats around the waist, Tongan-style. They paddle. They fish. They dance."

On the island of Lakeba (pronounced Lakemba), he writes that a shark-caller stands and chants in a lagoon each year to summon sharks.

It sounds unbelievable, the stuff of myth and legend, yet before our 11-night cruise to "places without postcards" ends, we will also experience villagers summoning nature with nothing more than the power of song.

Cruising from the Lau archipelago back to Viti Levu, we visit Kadavu Island - one of only two places in Fiji where the ritual of turtle calling is performed. It springs from a local legend about a Namuana princess and her daughter who went fishing only to be captured by warriors from a nearby village and thrown into their boat's hold.

When a storm threatens, the warriors discover the women are now turtles and, to save their own lives, throw them into the sea.

To summon the descendants of these turtles, Namuana's brightly clad women chant to a rhythm tapped out on a log while men scan the ocean from a cliff-top boulder.

Suddenly there's a shout; we rush to see what they're pointing at. Sure enough, a giant turtle floats to the surface, its flippers lazily working the water. It's not the only moment that will challenge our 21st-century beliefs.

Fiji is a destination within such easy reach - a mere four- to five-hour flight from Sydney - that it's difficult to grasp this cruise will take us "off the grid". Although the MV Reef Endeavour features on-board Wi-Fi, I'm told passengers aboard the inaugural Lau cruise late last year had only two days of connectivity.

I board Captain Cook Cruises' second Lau cruise on a Tuesday, wondering how on earth I'll run my work life. But I surprise myself by surrendering completely to the cocoon of on-board life.

Each day is a comforting routine of eating, drinking, snorkelling and exploring, with deviations such as hermit-crab races across the dance floor and an on-deck movie screening under the stars. The 100 passengers in this happy bubble include a bee farmer from New Zealand, a retired brewery worker from Wollongong, a young couple from Brisbane, a doctor from the United States and a retired pharmacist from Sydney.

Thirteen are here to dive the Listerine-coloured waters and their fantastical coral gardens, schools of fish and the odd stingray, shark and sea snake. Some are drawn by the new destination: after exploring Fiji's Mamanuca and Yasawa island chains, they're ready for something new.

Others are attracted by the cruise's languorous length. "Let's face it - I'm not here for the food," says one Sydney man. "It's just there to sustain you." Indeed, the dining is as patchy as the internet although the kitchen turns out a mean steak, perfectly cooked to order, and the best lunches are the outdoor barbecue and curry buffet days.

Two families with kids are also aboard - for very different reasons. Gwen Hause, 75, of Melbourne is travelling with her daughter and granddaughter. Hause's father, William Glanville Lau Cook, was born on Lakeba. His mother, May Cook, detailed her experiences as a missionary's wife in Fijian Diary 1904-1906: A Young Australian Woman's Account of Village Life in Fiji. The slim volume does the rounds of the ship, with the crew its most avid readers.

Disappointingly for Hause, we sail past Lakeba in the night (along with Mago Island, which Mel Gibson bought in 2005) but she still enjoys venturing near a place that looms large in her family history. "It's been such an experience," she says. "I think my grandmother must have been so brave to be here in the early 1900s."

The Lathleans from Sydney are celebrating dad Steve's 50th birthday. Steve and Laronne are cruising with Lucinda, 13, Isabelle, 11, Jasmin, 9, and twins Patricia and Zeke, 7. The kids make themselves at home straight away: Zeke often abandons his family to dine with other passengers and play chess with the bartender. One night Zeke writes a message, pops it in a bottle and tosses it overboard. Who does he hope will find it? "Someone from Wyndham," he says.

Fijian kids are another delight. We meet the first lot on Makogai Island after visiting a cemetery for the former occupants of the one-time leper colony. The island kids dance and sing; we donate money to their school.

On the "garden island" of Taveuni, a trek from stunning twin waterfalls brings us to a beachside picnic spot that's attracted an entire village. Before long, the ship kids are frolicking in the ocean with local kids who run straight into the water in their clothes.

We admire the patience of children attending an outdoor church service at Dakuiloa on Oneata Island. On a woven palm mat under threatening clouds, they try to not fidget as the barefoot minister's sermon drones on. Afterwards, I chat with Joana, 29, as her aunty chops open coconuts for us.

Poking around the classrooms of Naikeleyaga Village School on Kabara Island, we discover the rules include speaking in English and twice-daily tooth-brushing. That night, after a lovo feast baked in a hole on the beach, we finally see those crunchy mats Theroux mentioned. Women - including crew member Sera who hails from here - wrap them around their waist and sit cross-legged on the ground to dance and sing.

Our final school is Totoya Island's Navesi Primary School, which the cruise line officially supports. I'm expecting more cute performances but this visit's emotional - from the moment the kids form a rag-tag parade in front of the flagpole as a dog sits at its base, scratching fleas, to the girls wearing plastic bags wrapped around their waists instead of crunchy mats. Tears prick my eyes yet these kids have something invaluable: a glorious teacher, Ana Waqabaca, who can't help but join their dance routines.

It took three years of negotiations - over many shells of kava - for the line's managing director, former navy man Commander Semi Koroilavesau, to develop this route that takes in islands that normally see only supply boats every few weeks. Although he met with resistance initially, he says, "Now the other islands are saying, 'Why are you visiting that island and not us?'"

One of his most stressful moments came when a crew member was lost for two days as they worked out how to forge a trail to the interior lake of uninhabited Vuaqava Island. The man eventually followed a wild-goat track back to the beach and was rescued.

"We're going into virgin territory where no one's ever been before," says Koroilavesau of the Lau route. "We want to take passengers away from the normal places that tourists go and go into isolated places, and I think we're achieving it."

The itinerary includes awe-inspiring sights: the mushroom-shaped islets dotting Fulaga Lagoon and the swimmable limestone caves near Vanuabalavu Island are among the highlights. We're also confronted with the ravages of colonial history when we peek into a Vuaqava Island cave holding skulls - the victims of a cholera outbreak.

Yet the trip isn't so much about sights as it is about people. Koroilavesau says: "We believe staff are our main highlight for passengers, on top of going to developing places with no infrastructure." He's right. Many crew members remember my name from day one. They help us on and off tender boats and up and over rocky paths - one passenger struggling with sandal-sucking mud even scores herself a piggyback.

Those who linger after dinner for cross-legged gatherings around the tanoa (kava bowl) and the dancing see more warmth and personality from the crew.

A few days in, after island night when we're encouraged to wear a sulu (sarong) and bula shirt to dinner, everyone becomes looser and more relaxed. No passenger who stays up to party is ever left without a dance partner. Some probably don't intend to boogie across the carpet - but it's impossible to decline a tap on the shoulder from someone with the world's biggest smile.

The writer travelled as a guest of Captain Cook Cruises and Tourism Fiji.

FIVE MORE FIJI CRUISES

SHORT HOPS

South Sea Cruises offers day cruises out of Port Denarau including a family-friendly half-hour boat ride to South Sea Island and a full-day trip to Octopus Resort on Likuliku Bay in the Yasawas. See ssc.com.fj.

MODRIKI MAGIC

Blue Lagoon Cruises heads to the Yasawa and Mamanuca islands from Port Denarau, with itineraries ranging from three to seven nights. Highlights include Modriki Island, where Tom Hanks' movie Castaway was filmed. See bluelagooncruises.com.

GO P&O

P&O's Pacific Pearl 14-night round-trip Fiji Adventure departing Sydney in November visits Port Denarau near Nadi, the capital of Suva and Dravuni Island, which offers summit hiking and brilliant snorkelling. See pocruises.com.au.

ROYAL TOUR

Sun Princess cruises from Sydney to Fiji in November and January for 14 nights, calling in at Port Denarau, Suva, Dravuni Island and the dramatic harbour of Savusavu on the island of Vanua Levu. See princess.com.

FABULOUS FULAGA

Silversea's Silver Explorer visits the Southern Lau Group's Fulaga Island - with stunning mushroom-shaped islets emerging from the lagoon - on a 12-day sailing between Fiji and French Polynesia in October. See silversea.com.

TRIP NOTES

CRUISING THERE

Captain Cook Cruises' next 11-night Lau Islands Discovery Cruise departs Port Denarau on November 4; in 2015, it departs April 28, August 4 and November 3. Early-bird saver fares start from $3384 an adult twin-share. Fares include accommodation, meals, 24-hour tea and coffee, daily stopovers and water activities, guided village, school and island tours, snorkel and beach-towel hire, and glass bottom boat excursions. See captaincook.com.fj, phone (02) 9126 8160.

WHAT TO PACK

Clothes that cover knees and shoulders for village visits and church (a sulu combined with a bula shirt is acceptable attire); reef shoes, sandals or other footwear that can get wet; seasickness medication for any rough patches; storybooks and stationery for schools.

MORE INFORMATION

fiji.travel.