In whitewashed Strandkorbs, families huddle together, enjoying the last of the warmth from the faltering autumnal sun on their upturned faces. These striped beach baskets, some owned, others rented, are dotted along large expanses of windswept sands that seep into the inky Baltic sea.

The island of Usedom in Pomerania, surrounded by forests of beech trees, is known by some as the “bathtub of Berlin” and by others, slightly more poetically, as “sun island”. Dietrich Gildenhaar, a local author and guide, tells me that the island, north of the Szczecin lagoon in the huge Oder estuary, has been a luxury tourist destination since the Gründerzeit (Germany’s mid-19th-century economic boom), having been crowned one of the country’s sunniest places, with an annual average of more than 1,900 hours of sunshine. It is in two halves, the west side belonging to Germany and the eastern part to Poland, and has some of the region’s best beaches, with designated strips of sand for dogs and other sections reserved for nudists partaking in Freikörperkultur or “free body culture”.

However, despite being popular with Germans who flock to its spa resorts or explore inland on bike rides and long hikes, the island remains largely undiscovered by international visitors. In search of an alternative winter break, I’ve arrived to sample one of its many spas for some much-needed health and wellbeing maintenance.

On a Saturday afternoon in mid-October, with temperatures struggling to creep over 12C, the sky is dotted with colourful kites, many reaching dizzying heights above us. Most of the people on the seafront are German families in thick wool sweaters, who walk along the piers and bustle into coffee shops to escape the Baltic breeze.

We are in Bansin, one of three resort towns on the German side. Gildenhaar, standing outside a powder-blue house built in the Russian style, explains that many of the island’s buildings were financed by the wealthy German Delbrück family. Visitors included Russian poets, Berlin’s elite, and the king of Prussia, Wilhelm I; an annual parade in his honour is still held today.

“It was a place where you would often see nobility and aristocrats mixing with artists, and they would all come here for the wellness. Some of them were very ill and were ordered by their physicians to take the good air of Usedom,” he says.

Until the early 19th century, passengers arriving at the station were picked up in wooden carriages and transported to villas set back from the sea in private, landscaped gardens. All three of these coastal towns – Ahlbeck, Heringsdorf and Bansin – remain connected by rail.

The legacy of this aristocratic wealth has seeped into every corner of the architecture, and the island has an air of understated elegance, with many of the buildings now in private ownership and rented out as holiday homes. There are also many tastefully decorated hotels overlooking lawns behind the beach: ours is the Steigenberger Grandhotel and Spa in Heringsdorf, with its heated outdoor pool and saunas.

Another big draw of this region is the seafood. There are wood-fired huts for smoking fish dotted along the coastline, and nautical themes aplenty in the restaurants and hotels.

Close to the Polish border is the Fischräucherei Kamminke smokehouse, jutting out to sea. Large picture windows on its semi-enclosed veranda offer sparkling views over the Szczecin lagoon and create sun traps, protecting us from the bitter breeze. As we drink in the view, the waiters deliver huge plates of smoked butterfish fillet and stremel salmon, with steaming hot potatoes and dollops of braised cabbage. Our chunky wooden tables groan with the heavy plates, and the fish has a sweet pungency from the smoking process.

Further north there is Koserower Salzhütte, an old fishing hut converted into a restaurant, where only beechwood is used to smoke the fish. Its recipes have been passed down from a grandfather who, as a fisherman, owned two of these work huts and fished in nearby Koserow.

The restaurant’s owners have created a small museum telling the story of the island and its dependency on fishing. Herrings were particularly plentiful off this coast in the decades after 1815, and the Prussian state took measures to support the fishermen and supply the wider population. Under state supervision, the herrings were salted and stored in large wooden barrels, giving the fish a long shelf life. The salt huts on the site, also known as herring huts, date from that time and have been listed as historical monuments.

A small, dark dining room in one of these herring huts tempts us inside with smells of sea and wood and a promise of fish smoked in large wooden barrels. There is gravlax, entombed to perfection in coarse sea salt, served with a sweet cucumber dill salad that cleanses the palate with every mouthful; raw smoked herring, a delicacy that melts on the tongue; and large chunks of lightly fried halibut with the requisite cabbage and potato. All washed down with sweet German Scheurebe wine, it is a feast, an ode to the ocean.

The island has a haunting beauty. In his new film Usedom: A Clear View of the Sea, Heinz Brinkmann says: “When I was a child, the story of the discovery of my home town of Heringsdorf seemed like a fairytale. In spring 1863, the brothers Hugo and Adelbert Delbruük, bankers from Berlin, walking through a dense forest, proclaimed at the site of the Baltic sea: Here we will stay!” And it is indeed a fairytale.

The trip was provided by the German National Tourist board. Rooms at Steigenberger Grandhotel and Spa in Heringsdorf cost from €159.75.