The Big Island of Hawaii is no diving secret, but its world of underwater novelty never fails to amaze even the most seasoned diver. The fall-away blue waters off Kailua-Kona are home to the highest percentage of endemic species on the planet, and offshore night dives showcase creatures that make Alien look pedestrian. Here are four dive operators to help you blow some bubbles off the Big Island.

JACK'S DIVING LOCKER - Kailua-Kona

No dive operation on the Big Island is more synonymous with Hawaii ­diving than Jack’s Diving Locker. Its had time to establish itself; Jack Clothier, founder of the business, opened in 1981, back when Peter ­Frampton still had hair. Clothier has passed on, but in true ohana ­fashion, the PADI Instructor Development Center ambled its way into Jeff and Teri Leicher’s hands (young Jeff was one of Clothier’s students). And although Clothier would no longer recognize an operation that once consisted of five sets of gear and a Volkswagen van, he would recognize the easy, fun-loving attitude that remains.

When I first meet Jeff Leicher in front of Jack’s facility in Kona’s Coconut Grove Marketplace — heated dive pool, air-conditioned classrooms, state-of-the-art repair lab and gleaming retail store — he describes Jack’s Pelagic Magic night dive with a wry grin: “It’s like a space walk on acid. Not that I’ve done either.”

The next morning I dive with ­Leicher, boarding the Kea Nui and heading up the coast to a spot called LAX. The Kea Nui might be 46 feet long, but you’ll never find more than 18 divers on board. Jack’s operation is big and is run with military efficiency, but they know the value of intimacy. At LAX we fin above a cove smothered in plate corals, a lovely sweep that resembles a lettuce snowfield. This is surprising; Hawaii is long on volcanic structure and very, very short on such delicate corals. “No place else like it in Hawaii,” says Leicher, flashing what I now know is his trademark grin.

Yet even the jester can be surprised. On our very next dive, off the Natural Energy Lab, we watch a locust swarm of parrotfish spill and spill and spill past. Back on board, Leicher looks out at the blue water. “It’s been years since I’ve seen an aggregation like that.” He shakes his head. “That was comical.”

KONA DIVING COMPANY - Kailua-Kona

Ahhhh, the brownies — Kona Diving Company co-owner Kerry Key makes them and, post-dive, the lucky diver inhales them. As we board the sleek, 34-foot custom catamaran Hale Kai in Honokohau Harbor, a crew member waves a red-topped Tupperware container overhead. “OK, something important,” he says. “We’re kind of famous for this. Kerry makes these brownies every night.” Then, cruelly, he stashes them away.

Our baker is on board — Key is a very hands-on owner — and it’s a joy to dive with her. She sees everything — from a pregnant female whitetip shark tucked deep in a crevice to two tiny ­millet-seed butterflyfish, like lovely yellow teardrops from the sun. And she does it with panache: A giant green ­nudibranch bobs jauntily atop her hooded head. She also distills science in the same fashion, happy news for the layman. Explaining Hawaii’s high percentage of endemics (you won’t find a quarter of Hawaii’s fish anywhere else) she says, “We’re so far away from any land mass, they can’t go anywhere else.” As any diver knows, in a dive operation, attitude filters down from the top. During my time with PADI Dive Center Kona Diving Company, ­every hand reached out.

One last word of advice: Set aside some time for lounging in, well, the dive shop’s lounge. With Adirondack chairs, floor-to-ceiling murals and Jack Johnson wafting through the speakers, few dive shops feel more like home. And ask to see the wall. The building once housed a Harley Davidson shop, whose clients included rockers Neil Young and Steven Tyler and actor Dennis Hopper. In a corner, one of the three (you shouldn’t have to guess) has scrawled “Keep on Rockin.”

Key beams. “Isn’t that great? I love that wall. The wall stays.”

KONA HONU DIVERS - Kailua-Kona

Tonight will be a big night. A manta dive off Keahole Point and an open-ocean dive are both on tap, but here in ­Honokohau Harbor, the 46-foot Honu One is still lashed to the dock. Glenn Anderson doesn’t stand still often, but he stands still now, watching from the dock as his crew loads the boat. Anderson, who founded PADI Dive Center Kona Honu Divers with his wife, Maggie, is a big man with a capable manner, perhaps because, after 34 years of teaching high school machine shop, few things ruffle him. Aboard the Honu One, his crew conducts their business with easy laughter.

Anderson employs a two-part hiring system. He nods toward the boat.

“I may interview you and hire you, but if you get on the boat and they say” — Anderson turns both thumbs down — “then you’re gone.” We both watch the crew move about with swift economy. “The staff is trained properly. I’m very into education.” Anderson grins. “No surprise coming from a high school teacher.”

We dive first with the Big Island’s famed mantas, watching the winged ­giants swoop dreamily through the water in looping arcs. Although it doesn’t seem possible, the dream turns lovelier still when, several hours later, we prepare to drop into the open ocean, tethered to the Honu One so we won’t drift off into the deep. “What we’re about to see is otherworldly,” says our dive guide, Janine Maira, reverentially.

This is an ­understatement. In the dark sea — no Kona blue now — implausible, miniature wonders drift through our dive-light beams: gelatinous jellies, fingernail-size fish, creatures without comparison.

Back on the boat, a diver simply shakes his head.

“What a ridiculous night,” he says.

MAUNA LANI SEA ADVENTURES - Kohala Coast

Roughly 35 miles north from Kona along the Queen Ka’ahumanu Highway, the Kohala coast is pocked with luxe resorts, none more so than the Mauna Lani, with perfectly manicured golf courses ­rolling down to the loveliness of Maka’iwa Bay. But I’m not here to play golf. At the ­water’s edge, I check in at Mauna Lani Sea Adventures’ “office” — a small hut shaded by palms.

Small doesn’t mean fly-by-night though; the PADI resort has been in business since 1983. Thirty seconds from the dock, Capt. Gary Simons is hooting and throttling back, and the four of us on board are snatching up fins and masks, and falling over the side. For 15 minutes we cavort with streaking spinner dolphins, their chirps echoing through the blue. It’s a glorious treat, and somewhat rare. “We see them about once a week,” says Simons, “but they don’t usually hang around as long as they did. Today they were curious.”

Another 10 minutes and we’re in scuba gear. We dive each spot alone, not always the case off Kona. Tiny pom pom crabs put up their dukes, and green sea turtles drift by, orange eye and yellow tang cleaning them like loving tailgaters.

Here, time is not wasted on travel. Fifteen minutes up or down the coast puts you on top of some 30 dive spots. The dock is always close, and the boat returns to shore between dives, allowing for a hot shower and the chance to off-gas and tell dive lies while wrapped in a thick, soft towel, and sipping hot ­chocolate under the palms.

“We call it Gucci diving,” grins Simons.