She is probably as far from a modern passenger ferry as one can get but still in service between Stockholm and Mariehamn. Originally one of the Olympic ferries, built to carry passengers to the Olympic Games in Helsinki in 1952, but was delivered from Finnboda Varv in 1953 as the last of three ferries ordered.
She has been modernised a number of times and is therefore a modern ship despite her oldfashioned look. Some love her, others hate her and think she ought to be scrapped or, at least, retired from active service. You can read more about her here.