Blue Grotto, Capri: Inside Italy's incredible electric blue sea cave

Our local guide, Paolo, gathers us into a tight huddle on the crowded pier in Naples. At 7am, it's already oven-hot and humid, a sweaty shock after the air-conditioned comfort of the ship.

“Stay close to me, please,” he says. “At night when I need to sleep I don't count sheep, I count the faces of my passengers. It's a nightmare when I lose one of you in my mind.”

We're here for a tour of the Blue Grotto and Capri, a 10-hour excursion from Celebrity Cruises' Small Group Discoveries catalogue. Paolo has 12 of us to shepherd around today.

In another life, he might have been an actor or comedian, theatrically waving his hands and delivering lines with a smile and a wink. He spots a female acquaintance - “Ciao, bella signora!” - turns to the group and says, “When I see a beautiful woman, the sun rises inside me”.

We leave Naples behind, lapping up a cool breeze on the 50-minute ferry ride to glamorous Capri. Once a playground of Roman emperors, the island is now a summer magnet for the world's most famous celebrities. Hordes of tourists come seeking a slice of la dolce vita

We won't know until we reach Capri if the weather conditions are right for the Blue Grotto to open today. A legendary sea cave where the water appears to glow electric blue, the grotto's mouth is narrow, low and close to sea level. If the winds are a bit too high or the seas a bit too rough, it becomes impossible for rowboats to enter.

If it's closed, there are several other photogenic options nearby, including Arco Naturale (Natural Arch), a Paleolithic rock formation towering over the inky-blue Tyrrhenian Sea. "You saw it in the Dolce & Gabbana Light Blue ad, si?," Paolo says. “Mamma Mia!”

By the time we reach Capri, the news is good. The grotto is open today. Transferring from ferry to speedboat, we make waves past multi-million-dollar yachts where nut-brown women in white bikinis sun themselves on deck.

It's rush hour near the grotto's watery entrance and dozens of blue-and-white rowboats bob up and down, angling to get closer. Italian skippers with sun-ruddied faces and rough, strong hands handle the tides in an unflappable way that suggests they learned the ropes from their fathers and grandfathers before them.

One at a time, we climb over the side of the speedboat and drop clumsily into waiting rowboats. Our maritime Russian doll journey - from mega-ship to ferry, speedboat to rowboat - has surely reached its finale now that our vessel couldn't get much smaller. I'm touching toes with the other two passengers, my legs wedged between the standing skipper's, my sightline directed squarely at his crotch.

He motions us to lay flat and low as possible, as he pulls hard on the oars toward the cave's entrance. It's tight, oh so very tight, and I have to close my eyes and hold my breath as we whoosh through the jagged arc.

When I open my eyes and adjust to the darkness, we're floating inside a cool, tranquil womb. The seawater glows luminous blue, an otherworldly neon lake so perfect it might have been created at a Disney theme park. It's hushed and peaceful after the bustling carnival outside. As our skipper begins to sing O Sole Mio, his voice echoes off the rocky walls.

Time seems to stand still, though in truth we're in the cave for no more than 10 minutes. As we make our way back out into the jarring sunshine, attention turns again to earthly concerns.

“Tip? You like? You have tip for me? Tip, madam?” The skipper says it so many times, I soon have a few tips for him that don't involve cash.

An 11-night cruise in the Mediterranean on Celebrity Beyond in August 2023 from $4772 per person, twin share. It departs from Rome and stops at Sicily, Naples, Santorini, Athens, Istanbul and more. Drinks, wi-fi, tips included.

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