Since Groningen is a real student city, there is always a lot going on. Not only can you go to one of the many cultural hotspots that the city has to offer, you can also choose among a wide range of different activities being organised every single day. You can find many activities and events via Facebook, or just by reading all the posters and flyers at the university campus. But if you want a really nice overview of almost all of the activities that are being organised in Groningen, you can have a look at Here and Now.
Groningen has some great student societies (studievereningen in Dutch, better known as student associations in English), but there are also many other kinds of associations you could join. Think of sports associations, religious associations, cultural associations, international associations and study associations, among others. There is truly something for everyone. You can find more information about all these associations on GroningenLife.
The best way to get familiar with all the associations, events and hotspots in Groningen is to join one of the introduction weeks! These weeks are for students who are new in Groningen, and they are a great way to make your first friends in Groningen. Both KEI and ESN organise an introduction week for internationals, so you can choose - or maybe even join both. Read more about the introduction weeks in Groningen.