The amusement park is located in the outskirts of Reykjavík.   It is an outdoor park with mini golf, football golf, paintball and many other fun activities.    You can buy refreshments on site and on a clear day you can enjoy a lovely view over the city center.
It is open daily during summer (June, July and August), for other opening hours please see their website https://www.skemmtigardur.is/en/