There is one Ferry that does run all winter long, The Arni J. Richter between Door County and Washington Island. Watch it cut through the ice on these videos:

http://www.youtube.com/watch?v=UoP59gmb9Co&feature=related

You might recognize a few WILD and FORI members in this video:
http://www.youtube.com/watch?v=JzO8MroZMIw&feature=related


Suzanne Murphy
President, Wisconsin Lighthouse District (WILD)