From WENN.com

Hedlund arranged the romantic gesture in the early days of their courtship, but the stunt ended badly when the pair was forced to swim to shore through fetid water after they were thrown overboard.

He tells New York Post gossip colum Page Six, ""It was not a stable canoe. We fell out and had to swim back in mucky water... like golf-pond water.""

Dunst eventually forgave the TRON: Legacy star for the blunder and they have now been dating for a year.