Have you secured a ticket for the Fossavatn party in the Sports Hall and Torfnesi? A seafood buffet and a ball with the Fossavatnin support band led by Bigga Olgeir. You don't finish the Fossavatnsgang without finishing the prom.
You can buy tickets here, the ball is usually sold out so don't miss it https://fossavatn.is/product/fossavatnsparty/