I recently moved to Hamburg and the lake is quite beautiful! It is a great place to get some cardio in. There are always people running even later at night. It was amazing to be here to get to experience when the lake froze and had 20 cm of ice and the city declared it safe to go on. The Alstereisvergnügen was a great festival and despite the cold was an amazing experience. I believe it was the first time in 15 years that this happened so don't expect it again soon!