Sweden
Östhammar is a coastal municipality in Uppsala County, along the Baltic coast north of Stockholm at the start of the Uppsala archipelago. The historic Östhammar town and the long, narrow Gräsö island — accessible by ferry — anchor the sauna culture: island bastus on Gräsö and the outer archipelago are available for hire, and the Baltic coast reaches comfortable bathing temperatures in July and August. The municipality also contains Forsmark nuclear power station, creating an unexpected industrial presence in an otherwise pristine coastal landscape. Swedish etiquette throughout.
The historic town of Öregrund has traditional waterfront bathing culture and increasingly wood-fired barrel saunas with direct Baltic Sea access. Olands Spa covers the hotel sauna tier.
One of Sweden's best-preserved 18th-century wooden towns on the Uppland coast. Its harbour has traditional bathing facilities and sauna operators — the historic wooden-town setting makes it one of the most characterful Swedish sauna locations.
The Uppland coast reaches 18–20°C in July–August in protected bays, and drops to 1–3°C in winter. Ice bathing is practiced at maintained harbour spots.
