A night-time snorkel with manta rays is one of the top highlights of an Uncruise Adventure in the Hawaiian Islands. Photo / Getty Images
"Welcome to the manta mosh pit," our guide, Imran, from Hawaii's Kona Diving Company says. We're arriving at The Campfire, a 10m-deep area of Garden Eel Cove off the coast of the Big Island that's as busy as Auckland's Spaghetti Junction in rush hour.
Dozens of dive boats are bobbing in the darkness. Powerful lights illuminate groups in black wetsuits and snorkel gear who are tentatively clinging on to ropes on the sides of modified surfboards.
All of this traffic is here to see some of the 100-strong manta ray population off the island's Kona Coast, who must think their Christmas dinners have all come at once, almost every day of the year.
Many of this group return to feed at this special spot just off the coast of the island's main airport most nights of the week. The Big Island's dive squads make it as easy as possible for them, through a combination of elements that enhance their natural dining environment.
Each snorkeller has a glow stick attached to their wetsuit zip so the guides can keep track of their groups, while huge LED lights positioned on the ocean floor in a vague circle — hence "The Campfire"— light the scene from below. These glowing orbs are interspersed by more black-clad humans wearing scuba tanks and masks, adding their streams of bubbles to the scene's visual cacophony.
Amid all of this chaos are nine enormous manta rays, some up to 4m wide, performing graceful, balletic back flips as they feed. Their terrifying-looking but completely harmless oval mouths are wide open.
They're inhaling the plankton that has been attracted by the dive lights and caught in the current, powerless to do anything else but act as a sort of sushi train for the mantas' feeding pleasure. The plankton, lights and bubbles all combine to create an extraordinary snow globe-like effect swirling beneath us.
We're on the final night of a seven-night Hawaiian Seascapes cruise with UnCruise Adventures which we'd boarded in Molokai's tiny Kaunakakai Harbour the previous Saturday before heading east for the Big Island, exploring Lana'i and Maui on the way.
This is small-ship adventure sailing at its optimum. Think a maximum of 36 up-for-anything guests across 18 comfortable cabins on UnCruise's Hawaiian vessel, Safari Explorer, looked after by 16 multi-skilled, experienced crew.
During the week we enjoy fantastic food focused on regional specialities, plenty of time on and in Hawaii's warm waters and, best of all, a loose itinerary adjusted as required according to weather conditions or marine sightings so everyone on board — crew included — can get the most out of the eight days at sea.
It's educational too. Each night there's a marine life presentation by one of the knowledgeable Expedition Leaders, Ben or Sophy, or, on Manta Ray Day, by Ian from Kona Diving Company. He joins us on board to give us a run down on the biology and behaviours of the majestic creatures with whom we were about to spend 45 minutes in the water.
The first day is land-based and focused on Hawaiian culture, specifically that of an ancient part of Molokai's northwest called Halawa Valley. We travel in vans 90 minutes northeast on a narrow coastal road to meet Greg Solatorio who, along with his father Pilipo — the valley's last remaining elder - is a traditional Hawaiian culture kumu, or teacher. He welcomes us on to their land with a honi (known by New Zealanders as a hongī).
Some of us stay on to hear stories of the valley's history, including its devastation in a tsunami in 1946, how the family lives off the grid using traditional methods of gathering and preparing food, and how the Solatorios are doing their best to pass their culture on to future generations. The rest of the group go on a four-hour hike through the family's private land, passing ancient sites and crossing two rivers, to get to the beautiful Mo'oula Falls.
Our Lana'i day includes a couple of invigorating snorkels in the morning, including one at a deep-sea ocean drop-off point near its commercial seaport, Kaumalapau Harbour. Here, we see big schools of several varieties of butterflyfish as well as yellow tangs, trumpetfish, parrotfish, a few varieties of triggerfish, a gelatinous octopus, lots of colourful cauliflower coral and even a white-mouth moray eel.
Later, the skiffs drop us at Manele Bay on the southern side of this tiny island, which is 98 per cent owned by American billionaire Larry Ellison, of Oracle fame. We split up again, with some of our group choosing to spend the afternoon visiting the island's cat sanctuary, established to keep hundreds of feral cats away from burrowing sea birds and now home to more than 600 healthy, happy cats.
Others spend time at the beach or wander around the souvenir shops and galleries of quaint Lanai City, which is not a city at all, rather a small town square set around a park boasting dozens of tall Cook pine trees.
We all meet up towards sunset for a walk to one of the island's landmarks, Sweetheart Rock, or Pu'u Pehe, a basalt formation with a tragic legend attached. The story goes that the rock was the secret home of a maiden from Maui, Pehe, whose love for a warrior from Lana'i was forbidden.
Pehe drowned in a storm and when the warrior found her body, he carried it to the top of the rock, buried her and then jumped to his death. Her tomb can be seen on the top of the rock from the lookout opposite.
The following days fall into a blue-sky rhythm, punctuated by delicious meals and refreshing drinks after each excursion. When we're at anchor, sometimes the shelf is lowered at the back of Safari Explorer so we can swim, kayak or paddleboard; there's even a jumping platform which a few brave souls hurl themselves off doing tricks mid-air.
On several days there are kayak or skiff tours around points of interest, combining culture and history with geology and biology. One morning there's a fantastic hour in the water with more than 20 sea turtles at Mala Wharf, a wrecked pier on the western side of Maui.
One afternoon is dedicated to finding whales in the waters around Maui, Hawaii's hotspot for humpbacks. "They're my favourite creatures ever. I've probably been on 3500-3600 whale watches and I'll probably still be the most excited person on board," Expedition Leader Ben tells us. It's at least two weeks too early in the season to see many, he says, but we're rewarded with the awesome sight of a competition pod fighting over a female.
All of us are out on the deck with binoculars glued, watching nature at its most visceral. There are head lunges, there is dorsal fin and tail slapping by the female and there's a lot of grunting and aggressive bubble blowing from the males. There is blood. We'll never know who won because it's still going as we motor slowly away, leaving the massive creatures to continue their battle in private.
The morning of Manta Ray Day starts off promisingly, with breakfast delayed due to the sighting of a pod of rare Blainville's beaked whales. At lunchtime, we see our third variety of dolphin — pantropical spotted, which propel themselves at 90 degrees several feet into the air.
Ben is absolute fizzing and tells us the afternoon will be spent in deep ocean waters off the coast of the Big Island to see what other "big critters" we can find. Bingo — straight away a pod of short-fin pilot whales appears, accompanied by an oceanic white-tip shark, swiftly followed by a lone female reef manta ray feeding. It's a good sign for later, Sophy says. And so it turns out to be.
A seven-night Hawaiian Seascapes itinerary aboard the 36-passenger Safari Explorer starts from US$5595pp ($9176), twin share. Everything is included except for flights, crew gratuity (about US$250 per guest) and port fees and taxes.