Sørenga Seawater Pool is part of the modern Bjørvika expansion of Oslo, where they've built out wooden surfaces for chilling by the sea. It's a super popular spot on a sunny day, due to it being so central. At the very end, there's a little shallow pool perfect for kids, and a seawater pool for doing laps. Just be careful not to jump off the edge without checking the depth, as it can be a little shallow at times.

There are cafés, restaurants, toilets and ice creameries just next door as well. DNT (The Norwegian Trekking Association) also rent out kayaks, but you do need to have a course proof to rent (Check out other rental places like Mad Goat for kayaking).