The 80-hectare island is a part of Helsinki and during summer you can get there by boat from Vuosaari, Hakaniemi, or Laajasalo. On Vartiosaari half of the houses there are private, so be careful and don’t invade someone’s territory.
It’s perfect for birdwatching: besides common city birds, you can also meet waterfowl, waders, and some others.
The place is also suitable for day hiking. Though it is within the city limits you can enjoy picturesque scenery from the cliff looking at the sea, small islands, boats, ships, and even meet some sheep during summertime. The nature trail is pretty easy, so even inexperienced hikers won’t feel tired.