On the weekend (or in school holidays) it's worth checking out the playground areas in and around Ártúnsskóli. Sprawled across the pre school, school and a public park area you will find an impressive selection of play areas including a climbing wall and a zip wire.
nb - to find the zip wire - walk past the school, the climbing wall, basket ball court, football pitch, turn right and walk down the path for a few minutes. You can also get to it via Seiðakvisl. Looks like they are in the process of expanding the play area here so we will definitely be back to see what they build.
If you go in school time you won't be able to access all the areas i've shown in this blog.
Address Árkvörn 6, 110 Reykjavík