The festivities started Friday and run through Sunday. It's being billed as Germany's largest winter party and occurs when the river freezes over sufficiently to support a crowd.
The last outer Alster festival was 15 years ago. Weeks of below freezing temperature have made this year's party possible.
On Saturday afternoon there were impromptu ice hockey games taking place on the 164 hector river in the middle of the city. Others just skated. Some brought their children for a first time experience.
Hamburg residents weren't the only ones in on the fun. On the Masch lake in Hannover more than 100,000 people are expected over the weekend for another large ice party.
Skating fans should be sure to have their fun this weekend. Meteorologists are calling for some warmer temperatures next week that should push thermometers past the zero degree point.