I'm living in Stockholm for the next 3 months and I have some girlfriends coming into town at the end of the month. We are thinking about taking the ferry to Helsinki and hear that some are more like party boats. We're 20-somethings and wouldn't mind doing something like that. Which do you recommend? Also, I have been known to get sea-sick on occasion, how do you think the seas will be at the end of May? Should I be concerned?