Gudenå Open Water Event
With three different distances, the Familierute, the Medium, and the Long, varying from 1 to 5.7 km., there's a challenge level for everyone.
Sign-up for the event is open until the 25th of June at the regular price, with sign-ups on the day of the event having an extra 50 DKK charge.
Further information can be found at the Gudenå Open Water site (in Danish).
The Gudenå Open Water event is the second leg of The Danish Classics, which is a four-discipline challenge to test your skills and tenacity in cycling, swimming, running, and mountain biking. More info for The Danish Classics can be found on their website (in Danish).