All of a sudden, all that was dark morphs into light.
We're swimming through the inky, narrow cave opening to Hidden Beach where the sun, in contrast, is shining gloriously, illuminating the tiny bay a sparkling aquamarine, the beach a golden brown and the sky a brilliant azure.
My son, Alex, my daughter, Grace, and I are on the Snorkelling at Isla Marietas adventure (US$99 per person) organized by Ecotours de Mexico, an hour off the coast of Puerto Vallarta.
As we climb ashore, we're breathless and exhilarated to be in this enchanted enclave.
Our eyes automatically gravitate skyward in an effort to figure out where we are, how we got here and why Hidden Beach is such a stunning, geological rarity.
Hidden Beach is effectively mid-island, accessible only by the tapered cave we swam through. The opening to the sky, an oculus, if you will, is a perfect oval formed when the roof of the cave, which was also part of the island's surface, collapsed sometime in the 1990s.
The resulting crater isn't the usual ruin associated with such a ground cavity because the uncovered beach and water below is so spectacular.
Once we have the geology figured out, Alex, Grace and I wander the beach, splash in the water, check out the antechamber caves and chatter about how lucky we are to have discovered this paradise.
Well, maybe 'discovered' is too rich a word.
We wouldn't be here at all without Ecotours de Mexico and expedition leader Margarita Garcia.
Hidden Beach had become such a hot, international tourist destination that up to 2,500 people a day were showing up in all manner of boats, bumping into each other as they swam in and out and tramping the beach in a crowd.
The Mexican government stepped in 2016 and started limiting access to just 117 visitors a day to Hidden Beach.
More are allowed on Maietas' regular beaches and surrounding waters for snorkelling.
However, Hidden Beach is the hot ticket any only vetted tour operators can get permits for their guests to hit the crater.
That's why Ecotours de Mexico brings only 10 tourists a day to Marietas in a nimble Zodiac for the exclusive Hidden Beach excursion.
As an added bonus, our group also snorkelled, ran through the rock arches at La Nopalera Beach and enjoyed humpback whale and dolphin sightings on the way there and back.
My wife, Kerry, and I touted our two weeks in Nuevo Vallarta as the best-of-both-worlds.
Kerry found an ideally-located condominium for us on VRBO in Bahia del Sol Resort, where the view is all pool, palm trees, 10 kilometres of beach and the Pacific Ocean.
We had the first week to ourselves for long beach walks, cycling, lounging on the beach and poolside, wine at sunset and dinners at nearby authentic Mexican restaurants La Isla, Coco Beach and Riviera Grill.
For the second week, our grownup kids joined us for the Hidden Island excursion, more beach and pool time, discovering Taco Cabana and Fajita Republic restaurants nearby and hitting the beach club and restaurant scene off Puerto Vallarta's famous Malecon.
Puerto Vallarta and its surrounds is one of the most popular sun destinations for Canadians.
As such, Air Canada, WestJet, Sunwing, Air Transat and Swoop fly non-stop to Puerto Vallarta from a myriad of Canadian cities, including Calgary, Edmonton, Winnipeg, Vancouver, Victoria, Kelowna, Toronto, Montreal and Ottawa.
My family took advantage of Air Canada's partnership with Switch Health to do the rapid antigen COVID test required for re-entry to Canada.
We ordered two, 2-pack COVID-19 Rapid Antigen Test Kits online at SwitchHealth.ca/en/partners/aeroplan ($129 or $79 for Air Canada Aeroplan members) and had them delivered to our home.
We took the kits along to Mexico and the day before flying out we did the tests ourselves with a Switch Health representative watching during a telehealth session.
The test results (negative for all four of us, yay!) were uploaded and Switch Health sent the downloadable and printable confirmation required for ArriveCAN via email right away.
It was much cheaper and more convenient than figuring out testing at a Mexican facility.
