Most visitors to Antigua come for the warmth, the sunshine, the aquamarine sea, and the Crayola-hued fish that dart around the coral reef.

Not us. We were hoping to enter an Antiguan realm that was dark, cool and guano-covered — Bat Cave. Rumor has it that this cave system stretches all the way to the island of Guadalupe. Or was that merely an urban — or island — myth? We’ve belly-crawled in caves from Bozeman to Belize, and are always up for exploring the musty mysteries of another cavern.

A little sleuthing revealed we’d need a pass from the Antigua park service to enter Bat Cave, 24 hours before entry. And then they inquired about our identities: we were university scientists, were we not? Um, nope. Buh-bye, Bat Cave.

“I think the cave is crumbling inside, and isn’t safe to visit,” a local naturalist told us later. Whatever. We couldn’t lure Miami Herald readers to a cave that wasn’t open, even if we had managed to sweet-talk (or lie) our way in.

We quickly learned that Antigua has lots of other enchantments, besides the forbidden cave, for those of us who are too energetic to sit on a beach all day. “You need to hook up with Eli Fuller,” our charming hotelier at Sugar Ridge Resort, Annie McCauley, told us. “He knows anything and everything about the outdoors here,” she said. “He’s a former Olympian, and he grew up on the island.” Fuller runs eco-tours, and calls his company Adventure Antigua. Perfecto!

An all-day tour on Fuller’s 52-foot power catamaran reveals the glories of this West Indies isle that most visitors miss. Plus, there are opportunities to snorkel, swim, hike, and … enter a cave. Well, sort of.

With yacht captain Ross Bloomfield at the wheel, we motored out of Jolly Harbor, up the west coast of Antigua, past beaches accessible only by boat. They say that the island has 365 beaches, one for each day of the year — after a day exploring the island, you won’t doubt it.

“Every beach on Antigua is public,” Bloomfield said, indicating a designated nude beach near the Hawksbill hotel. “We don’t want to get too close,” he added, “the average age is 93 over there.” Spoken like a true 20-something.

Overhead, brown boobies and frigate birds swirled; rising before us were velvety green hillocks dotted with stone sugar mills, among 80 or so of these that still stand, dating back to the 1700s and 1800s when the island was a major sugar producer. Nowadays, these are used as shops, even homes.

One of our most interesting stops was Great Bird Island, one of 40 offshore islands surrounding Antigua; all are national parks. We saw trees covered with nesting brown pelicans and a riot of red-billed tropic birds (thus the name), but another creature is the star attraction here: a sandy-colored, speckled snake called the Antigua Racer.

“They’re gentle and harmless, and they’re the rarest snake in the world,” said Nicola Ross, a marine biologist who is part of the Adventure Antigua crew. There are only 310 of these snakes on the planet, Ross said; Great Bird Island is a sanctuary for them.

We hiked up a small hill, and were rewarded with lovely views of aqua water and tawny patches of reef — and a splash, when a spotted eagle ray pirouetted into the water. If you’re lucky, you can see humpback whales and bottlenose and spinner dolphins here in winter, Ross said. “And if you’re really lucky, you’ll see one of these,” she added, displaying an Antigua Racer she’d discover on the trailside. Those who hadn’t hiked scrambled off the boat to see this rare reptile. “I think this snake is having a Justin Bieber moment,” someone said as the cameras snapped.