More than 330 islands shelter the waters south of Helsinki, a granite labyrinth carved by retreating ice 10,000 years ago and claimed by Swedes, Russians, and Finns in turn. By the mid-19th century, steamships began threading these channels, ferrying merchants and summer residents between city and villa. Today the same routes carry vessels that depart each evening from Kauppatori, the harbor square where herring vendors and flower stalls give way to boarding passengers at half past six. The two-hour circuit traces the inner archipelago, a zone of forested islets and red-painted villas that begins at Suomenlinna—the sea fortress UNESCO inscribed in 1991—and extends southeast past Vallisaari, a former military reserve opened to the public in 2016. Navigation lights mark shallow passages between islands no larger than a tennis court. Limestone foundations of 18th-century barracks rise above the waterline on some; others support only a single spruce and a bird blind. The Finnish military controlled most of these islands until the 1990s, preserving them from development and leaving ecosystems that now host nesting terns and rare orchids. Vessel design follows Baltic tradition: wide-beam hulls for stability in open water, shallow draft for island approaches, open deck space for the 21:30 summer sunset. The standard adult ticket covers two hours of sailing with onboard commentary available in Finnish, Swedish, and English. Departures run Monday, Wednesday, Thursday, Friday, and Saturday from late April through September, when daylight extends past ten o'clock and water temperatures reach 17 degrees Celsius. Boarding begins thirty minutes before departure; passengers arriving at 18:30 secure preferred seating on the upper deck. The cruise operates regardless of weather—Helsinki records rain on 180 days per year—and vessels carry indoor seating with panoramic windows. Onboard service includes coffee, beer brewed on Suomenlinna, and cinnamon buns from a Market Square bakery. The route returns passengers to Kauppatori by 20:30, in time for the evening fish market and the last tram connections to Kallio and Töölö.