Hattusaari

https://www.hel.fi/helsinki/en/culture/recreation/islands/other-islands

<p>Hattusaari in the Eastern Helsinki archipelago offers an excellent view towards the open sea. The 2,6h island is a nature reserve, mostly open and treeless, and a popular bird nesting area.
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<p>Short term camping in a tent is possible, however there is not public transport and any public services other than a toilet on the island.</p>