Surrounded by sea and a vast archipelago, Helsinki is at its best in the summer when the dialogue between the city and nature is at its fullest. Classical Helsinki's sights can be divided into an eclectic set of churches and a wide variety of museums. For a coastal amble past some of Helsinki's minor and major sights, see the itinerary A seaside stroll in Helsinki.

Suomenlinna
If you see only one place in Helsinki in the summer, make it Suomenlinna. The "Gibraltar of the North" was once the greatest sea fortress in the Baltic, built by the Swedish in the mid-1700s at great expense to protect their eastern flank. But when the Russians invaded in February 1808, the bulk of the unprepared and bankrupt Swedish army hastily withdrew, allowing the Russians to conquer Helsinki without a fight and besiege the fortress. With no reinforcements in sight, commander Carl Olof Cronstedt surrendered unconditionally two months later, and Finland was ceded to the Russians. Cronstedt's actions probably saved countless civilian lives, but King Gustav IV needed a scapegoat and sentenced him to death for treason; fortunately, the losing king was himself soon overthrown, and Cronstadt lived out his years gardening.

Today's Suomenlinna is still living in its own time with only old buildings, few cars, fewer than a thousand inhabitants and lots of old fortifications, catacombs and cast iron cannons. But it's not just a museum: the sprawling complex houses restaurants, cafes, theaters and museums, and is a very popular place for a picnic on a fine summer day, watching the vast passenger ferries drift by on their way to Estonia and St Petersburg. It was included in UNESCO's World Heritage List in 1991 as a unique monument to European military architecture.

Entry to the island is free. The HKL ferry from Market Square is the cheapest and most convenient of getting there at ?3.80 for a 12-hour tourist return. Guided tours in English are available daily at 11AM and 2PM in Jun-Aug and on Sat/Sun only at 1:30PM the rest of the year, ?7/person, and history buffs will want to drop into the Suomenlinna Museum at the Visitor Centre (?5).

Other islands

A beautiful archipelago (saaristo) surrounds the Helsinki city center. In addition to the major islands listed below, there are scheduled services to many smaller islands, and you can also tour them by sightseeing cruise. Most of the cruises depart from the Western corner of the Market Square and last from one to several hours. Note most ferries and cruises operate only in the summer high season.

Seurasaari Open Air Museum. A pleasant little island to the north of the center, filled with walking trails and authentic old Finnish houses collected from all over the country. An excellent half-day trip, especially in the summer, when many buildings have guides practising crafts in traditional dress. There's a very pleasant if somewhat pricy summer cafe/restaurant atop a small hill at the center of the island. Entry to the park free, entry into the museum buildings ?5 (buy tickets at entrance). Take bus 24 from Erottaja at the northern end of Esplanadi to the terminus (20-30 minutes), then walk across the bridge. Beware of mercenary squirrels that will raid your bags if you carry any food.
Pihlajasaari. Few tourists find their way here, but this is a very popular summer spot for Helsinkians, with sandy beaches (including a mixed nude beach) and a restaurant dishing out cold beer and ciders. Ferries run from Merisatama pier at the southern end of Kaivopuisto Park (tram 3B) hourly from 9:30AM to 8:30PM, 10-15 min, ?5.50 return.
Korkeasaari. A large island in central Helsinki best known for Helsinki Zoo, with approximately 200 different animal species. Connected to the mainland by bridge (bus 11 from Central Railway Station), in summer you can also open for a 15-min ferry ride from Hakaniemi and Market Square. Entry to the zoo ?10/5 adult/child.

Parks

Esplanadi Park. Located between Market Square (Kauppatori) and the two Esplanadi boulevards, this small but stately park has a commanding position at the heart of the city. In the summer time it is full of people sitting on the lawn, meeting their friends and quite often also having a drink or two. In the summer there are often free concerts given by local artists on the stage close to Kauppatori, facing restaurant Kappeli. If you're walking around with an ice cream or sandwich, do watch out for the aggressive birds.
Kaivopuisto. A beautiful park by the sea in the southernmost part of the city. In summer you might want to sit down for a cup of coffee in one of the seaside cafes and enjoy the view of sailboats and the people on the promenade. Housing surrounding this area is the most expensive in Helsinki.
 
A view over TöölönlahtiTöölönlahti. Located northwest from the central railway station, this is a bay surrounded by a nice park that is dotted with attractions such as the Finlandia Concert Hall and the National Opera. Töölönlahti is partly in a natural state which is quite rare in major cities. Walking and jogging around the bay is a popular outdoor activity.
Sinebrychoffin puisto. Also known as "Koffin puisto", located in Punavuori district next to the Sinebrychoff art museum. Popular with young people, in the summer it is full of people having picnics or just drinking pussikalja (literally: "beer in a bag"), while in the winter kids ride sleds down the snowy slope.
Central Park (Keskuspuisto). This is a huge park starting just north of the Olympic Stadium and extending for 10 km north. It encompasses an area of over 1,000 hectares. The park is mostly in a natural state.
Alppipuisto. Located on the west side of the Linnanmäki amusement park, this beautiful park is a hidden gem during the summer due to the many free concerts and other events that are held there throughout the summer months.