Tarhakäärme is another name for rantakäärme, usually easy to recognise from the yellow marks at the neck. While adders can have a varying colouring with a clear zigzag pattern to completely black. They can also often be seen swimming. The third one is kangaskäärme, who only live in Ahvenanmaa/Åland, not in mainland Finland. And some might think that vaskitsa or copper snake (slowworm) is a snake because it looks like one, but it's a lizard without legs.