Pihlajasaari is possibly the most scenic bouldering area of Helsinki. Few minutes public transport boat trip from Eira / cafe Carusel and you will find yourself in quietness and in classic archipelago forests. (Public boats operate only May-September!)
Island is quite big so there is always option to go to less/more windy or sunny sector. When it´s cold and windy on other side, it might still be very hot on the opposite side of the island. Rock quality is smooth granite with mostly crimps and some amazingly good slopers. Grades vary from very easy to very hard and from low to highballs so there is something for everyone here. Recommendation is to go with friends to get many pads and a spotter which will make things easier. With a single crashpad you can enjoy sectors Rantaslabit, Hiekkaranta and left side of Metsä. Rest of the sectors you will probably need 2 pads or more.
The island has a restaurant with a terrace near sector Ranta offering some lunch options, cold beers, coffee etc. There is also a camping ground with firewoods included for BBQ, drinkable water tap, many open toilets, beaches for swimming and sunbathing, a cafe/kiosk and 2 reservation saunas, one on both end of the island.