On Lake Geneva, the mail comes by boat
From the article: "...Known as jumpers, these special carriers leap from the moving boat onto piers to run the mail to mailboxes, collect outgoing mail and then jump back onto the boat, which is moving at 5 mph. The jumpers serve 75 homes along the shore. ... Applicants are also required to have at least one year of experience as an employee of the Lake Geneva Cruise Line, which operates the mailboat. ... USPS resumes normal delivery for the lakeside addresses once the season, which runs mid-June to mid-September, ends. ..."
Article Reference: usps.com