Chill out in the afternoon sunshine on the terrace by the Paterswoldermeer lake. In the weekends there’s often a DJ cranking out lounge tunes. Anything goes here and there’s an outdoor bar to keep you refreshed, so no need to rely on crappy NL service. The crowd is mostly a kind of young professional, a type you don’t see so often in the evenings in Groningen.
There’s also decent food and really good platters for when you get hungry.
You’re right beside the lake, so watch (or join) the water skiing club, or pop around the corner to the lake beach and the icecream shop.