Pllek - relaxed place located in the alternative district of Amsterdam Noord. Especially recommended during summer, when you can enjoy yourself in the sandy terrace and even take a swim! The place also organizes many exhibitions and yoga sessions.
Roest - one of the chillest places in Amsterdam, especially in the Not only has an unique decorative style, but also offers an artificial beach just next to the canal. Perfect place to grab a beer in the sun and relax.
Pluk de Nacht - Open Air Film Festival happening in August. Pretty interesting selection of movies and what is more important: free movies. The festival is donation-based though so chip in a bit to support this amazing initiative.