Vallisaari (and its two immediate neighbors), originally outliers of the 18th-century Suomenlinna sea fortress, were closed to public access until recently due to their military functions. Now they are popular and rewarding destinations from May to September (and at other times, if you can befriend a private-boat owner). Water bus services run to the islands in the Helsinki archipelago, making the 20–25-minute voyage from a quay near the old Market Hall in the South Harbour to the two connected islands of Vallisaari and Kuninkaansaari and to Lonna, the tiniest of the three with a fine restaurant and host of a summer jazz festival. On Vallisaari, the largest of the three, visitors must stick to the trails running through designated areas to protect the unique and beautifully wooded natural environment—as well as to avoid the site of historic munitions explosions. The trail leads to a viewing platform above the fortifications. The views are glorious, stretching back to the city across Suomenlinna and out to the open sea, and there is the occasional spectacle of cruise ships and ferries slipping through the narrow straits between islands. Vallisaari has a quayside café and bar, picnic benches, and a marina for visiting boats. Guided nature, history, and photography tours are available through Finland National Parks, which maintains and manages the island. One can reach the smaller Kuninkaansaari from Vallisaari across a short causeway and explore the old gun emplacements.