I fell for Ischia well before I ever visited it in person. In the 1999 film “The Talented Mr. Ripley,” the scene where Tom, the main character, “happens” upon Marge and Dickie, the couple he is pursuing, was filmed beneath the island’s Aragonese castle on its golden beach (the Spiaggia dei Pescatori, the beach of the fishermen). The couple’s beautiful, tanned physiques and relaxed smiles, the perfect sand and tranquil sea, were a cinematic ad to move to Italy, and to Ischia, immediately.

Ischia is one of a trio of islands (known as the Phlegraeans) off Naples that also includes Capri and Procida. Capri’s size and popularity with day trippers means it can easily feel overrun and overexposed. Procida is the smallest of the three and has never gotten the attention of its siblings (although it too is worth a visit for its pastel villages and artisan workshops).

Ischia’s magic is that it’s suspended between the newly chic — with the recent overhaul of the Mezzatorre Hotel by the hotelier Marie-Louise Sció, who brought a crowd that had never heard of the island but were fans of her über-photogenic hotels — and the authentic. There are simple bars, beach clubs and harbors more likely to dock fishing boats than megayachts. With a surface area of almost 18 square miles, the island is home to a number of charming villages to explore like Forio, Ischia Ponte, Sant’Angelo and Casamicciola, among others. Add in natural thermal spas, lush vineyards and deserted coves, and it’s easy to see why Ischia is quickly become one of Italy’s rising destinations.

My first morning on the island, it is raining so hard I head to the spa at Mezzatorre above Forio. Many of the properties on Ischia are built on top of the island’s thermal springs, a gift freely given by the still active volcano at the island’s heart. According to myth, Zeus vanquished Tifeo, one of the Titans who tried to attack Olympus, underground here and the trapped god’s angry breath created thermal springs and fumaroles. The spas here have a strong medical component and the main attractions are the island’s therapeutic mud and waters of various temperatures that gurgle their way from underground to combat rheumatism, respiratory issues and skin conditions like dermatosis. (At Sant’Angelo, the beach is so hot that locals cook eggs and rabbit under the sand.)

Dr. Giulio Uggiano is Mezzatorre’s resident doctor, a kind older man who takes my blood pressure, examines my nose and ears, and listens to my heart before giving me the go-ahead for a mud treatment. I have a bit of congestion in my lungs, he says. Amedeo, my technician, also a kind, grandfatherly type and a longtime Mezzatorre employee, covers me with hot green mud and wraps me in plastic. I ask him about his family as he trusses me. He is one of 12 children and has worked with the water’s healing properties since he was 14. I feel a bit like a basted turkey, but it’s also incredibly relaxing and warm on this chilly Monday to stew in my own juices. After half an hour, I shower off the leftover mud, before taking to the three pools of various temperatures. My congestion does feel lighter, and my skin shines.

Mezzatorre has arguably the most idyllic position of all the island’s hotels: It’s perched on a finger of land, with a craggy cove, a rocky promontory for sun worshippers, a view onto the bay of Naples and the beach of San Montano below. Ms. Sció reopened the hotel in the summer of 2019, before the pandemic hit. Her other properties, which include J. Paul Getty’s former villa, La Posta Vecchia, outside Rome, already have a high-wattage following. “Ischia is the real deal,” she said about her decision to open a property here. “It’s wild and wonderful. And I don’t like obvious places.”

Ms. Sció and the owners of many other hotels and restaurants on the island have joined forces to form a conglomerate called Ischia Is More to highlight the island’s diverse attractions, everything from its film festival in July to the hikes up Mount Epomeo, the island’s highest peak, which are particularly beautiful in late spring when the wildflowers bloom.

Castello Aragonese, in the town of Ischia Ponte, is one of Ischia’s musts, both for its views and history. First built in 474 B.C., the castle as it stands now was constructed by King Alfonso of Aragon in the 1400s, with art-installation-worthy ramps, lookouts and interior courtyards (12-euro entry). The 1963 movie “Cleopatra,” starring Liz Taylor and Richard Burton, was, in part, filmed here, and the two actors, married, but not to each other, started a full-blown affair on Ischia, to the delight of the paparazzi.

The frescoes from Giotto’s school in the castle’s Cattedrale dell’ Assunta are spectacular as are the views of Capri from the top, but I am most struck by the monks’ crypt, which is only a couple of tiny rooms in size, windowless and low-ceilinged. The corpses of the deceased brothers were brought here, and placed on stone benches with their necks and hands chained to keep them upright while they decomposed. Living devotees would come and take the draining liquid to dispose of their bile until all that remained were the skeletons and chains. The air in these rooms was so toxic that the younger monks would often die from the fumes. I shudder, but it helps me appreciate the sea air even more when I get outside.

The story of another great attraction, the botanical gardens of La Mortella in Forio actually starts in Buenos Aires in 1948, where the composer William Walton met his Argentine bride, Susana. After a fruitless search for a property they liked on the Amalfi Coast, they came to Ischia instead. Walton bought her five acres of land and she set out, with the help of the renowned garden designer Russell Page, to create a world-famous garden inspired at least partly by Spain’s Alhambra Palace. The microclimate, protected by the mountain, is a fertile valley full of stone pine trees, Brazilian flame trees, Arabic fountains, birds of paradise, magnolia trees and lotuses, papyrus, and hot and wet orchids, among other horticultural treasures (€12 entry).

On a Thursday morning, the island is waking up. A bagnino (lifeguard) is raking sand in front of a beach club. An older man stops into a cafe with his two dogs for a morning coffee and a pack of cigarettes. The church bell rings. The sun shines. A handsome local whom I have seen on my daily runs, smiles at me as he passes. I love the early mornings here. Traveling these days, I find I have to be increasingly strategic in my timing to see the authenticity of a place; Italy in general is experiencing a popularity that I have never seen in the 20 years I have lived here.

In the 1950s, when Truman Capote retreated here with his partner Jack Dunphy, few of Capote’s peers would have heard of this Mediterranean island, let alone visited. Which is exactly why he came to Ischia to work. He and Dunphy bunked at Ischia’s Pensione di Lustro for $200 a month, which included two five-course meals daily. (Tennessee Williams joined them briefly.)

The island made an appearance in both Elena Ferrante’s “My Brilliant Friend” novel and its spectacular HBO adaptation as the spot where the two teenage protagonists holiday: Mules carry their luggage up the steep cobblestone streets of Sant’Angelo, Elena loses her virginity on a moonlit beach, and the girls cavort on the thermal beach of Maronti. Like the girls, the reader relaxes into Ischia’s easy summer rhythms, away from stultifying and violent Naples. Ms. Ferrante writes, “Now the moon was visible amid scattered pale-edged clouds; the evening was very fragrant, and you could hear the hypnotic rhythm of the waves.” I am right there with her.

Perhaps the best way to spend a day on Ischia is by exploring the coast by motorboat, a much less expensive undertaking than on Capri or along the Amalfi Coast. On this day, my captain-guide is Giuseppe Puzella, and we chat as we head along the seafront. He left the island for many years to work for Carnival Cruises and then to London for another cruise line. But he always yearned to start a business on the island where he was born. “The slickness of Capri and Amalfi is missing here,” Mr. Puzella said. “It’s a working island which promotes tourism but wants to stay livable.”

We also talk about the heavy rain that caused a mudslide in the tiny town of Casamicciola last year, destroying homes and killing 11 residents.

We fall into easy silence as we pass O’Vagnitiello, a beautiful bay with transparent water surrounded by rocky outcroppings, and then San Pancrazio with its green grotto. This is the most solitary stretch of the island, with just the occasional sea bird whirling and crying out. We stop at Sorgeto, a set of natural rock pools filled by hot spring water right on the shoreline. I jump from the boat into the cold sea and swim as fast as I can to the warmth of the pools.

My first dip of the year makes me hungry and Mr. Puzella suggests lunch at Le Fumarole da Nicola, a family-owned restaurant by the sea that’s been around since 1950 near Sant’Angelo. A water taxi that costs a couple of euros takes us from our boat to the trattoria, which sits above the sea, and where we eat calamari and artichokes, sea bass and sun-ripened tomatoes.

Underneath the restaurant the family has created a natural sauna and hot pool from the thermal water that runs beneath it. It’s a trio of water treatments: a sauna in a rocky cave that’s seriously hot, followed by a jump into the sea and then a hot pool. I repeat the process a few times and then lie on the beach watching the fishing boats pass by. It’s the perfect simple day.

Ischia is just over an hour’s ferry ride from the main port of Naples, Napoli Beverello, and many of the hotels on the island offer free transfers from the ferry dock on the island.

The most upscale hotels, like the Mezzatorre Hotel and Thermal Spa, include destination spas — don’t miss the mud treatment (doubles from €495). The Regina Isabella, an old school grande dame on the water, also has a Michelin-starred restaurant, Indaco, run by the chef Pasquale Palamaro, and worth a meal even if you don’t stay there, doubles from €335).

The newly opened Botania Relais has the island’s ravishing vegetarian restaurant, Il Mirto (doubles from €350), while another grande dame, the San Montano Resort and Spa, recently opened chic new rooms from its birds’ nest location (doubles from €350, with free transfer to the great beach below). And Costa del Capitano has equally evocative views from its recently refurbished property above the sea near the picturesque village of Sant’Angelo (one-bedroom apartments from €470).

Just steps from Castello Aragonese, locals come to the restaurant Coco as frequently as tourists for its authentic seasonal dishes and the prices, which are very reasonable considering its prime position (Ponte Aragonese 1, no website). Nearby Giardino Eden is a must for its romantic position on the sea with the castle looming above — be sure to book well in advance — if you are looking for a beach club with a view, this is one of the best on Ischia.

For lunch, book a table at La Scannella, with its fabulous location overlooking the sea — the mozzarella comes from the owner’s buffalo nearby — and you can also reserve beach loungers and umbrellas below. If your itinerary includes a hike up Mount Epomeo, don’t miss lunch at La Grotta di Fiore (Via Epomeo, 21) for bruschetta and the island’s signature dish, rabbit.

The guide and captain Giuseppe Puzella recently launched Nestori Yachting and organizes boat trips both around Ischia as well as Capri and the Amalfi Coast (half-day tours, €650).

Based in Italy, Ondine Cohane, writes frequently for Travel. She is a co-author of “Always Italy,” published by National Geographic, and is currently writing a memoir.


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