Seljavallalaug pool in the South of Iceland was my favorite off the beaten path thing that we did in Iceland. It was built by locals in 1923 so that more Icelanders could learn how to swim. The entire area is a photographers dream! There are some basalt columns at the beginning and then it’s a pretty easy hike through beautiful mountain scenery to the pool. You do have to cross a stream but we didn’t find it difficult. If you are planning on swimming I do recommend it in the warmer months. We dipped in March and it was warm as it is fed by hot springs but not warm enough with the cold air. Even if you don’t swim the hike there is gorgeous, I really enjoyed the various rock formations.