Prior to 1944 the island was for centuries populated by ethnic Swedes and traditional Swedish law was used. Ruhnu has currently less than 100, mostly ethnic Estonian permanent inhabitants who like to keep to themselves.
You can reach pretty much everything by walking.
If arriving by airplane, there is a free shuttle bus to the village. Tell the bus driver the name of the place of family where you are staying, he will take you there. The same for getting to airport - ask your host to call the bus, it will pick you up.
St. Madeline's Church in Ruhnu. It's the oldest known wooden building still standing in Estonia - its construction was started in 1643.edit
Ruhnu's New Church. The new church was build only two meters from the old wooden church. The walls of the church are made from rocks and the church tower from wood. The church bell is one of the oldest in Estonia.edit
There are few small shops on the island. Write down their opening times, because they may not be open all day long.
As in mainland Estonia, the official currency is EUR. Credit and debit cards are usually accepted.