The Port Huron Float Down is an annual tradition of folks gathering on inner tubes and rafts to lazily float from Port Huron's Lighthouse Beach to Chrysler Beach in Marysville some 5 miles down the St. Clair River. This year, however, the unofficial and unsanctioned annual event became an accidental invasion as 1,500 of the revelers drifted into the Canadian side of the St. Clair River and needed rescuing.

According to the CBC, strong winds, some up to 27 knots, blew the Americans across the river to Sarnia, Ontario. Many of the Americans had been drinking and lacked forms of identification, and, as a result attempted to swim back to the U.S. side when the Canadian Coast Guard — aided by the Sarnia police, the Ontario Provincial Police, the Canada Border Service Agency and employees from a nearby chemical company — attempted to rescue the unwitting tourists.

"They were terrified of entering another country without documentation. No one carries their passport or any ID, and a lot were drinking alcohol," Peter Garapick of the Canadian Coast Guard told the CBC.

Once the Americans had been rescued, they were taken back to the U.S. on Sarnia Transit buses, complete with police escorts. Given the number of Americans, it took 19 trips to the border and was estimated to cost Ontario more than CA$8,000 (about $6,000 in U.S. funds) in transportation, manpower and clean-up.

1,500 U.S. partiers accidentally invade Canada
The Americans were participating in the annual Port Huron Float Down when strong winds blew them over the border.