On Thursday we had breakfast, got dressed again and got our swimming costumes because we had gone to the nature baths. Nature baths were huge swimming pool like sizes filled with natural water and heated by the lava underground. This is called geothermal power. But before we did that we had a stop and strolled along a huge rocky island. There were little caves and pools of water. After we went to the nature baths when you went out it was freezing cold. But then you got in the pool and it was so warm. In some parts the water was hotter than other parts. I even collected some actual real lava rock. We spent ages in the pool and it was amazing. After a long time of warm water we got out and went for a snack, drove home and had a rest. A little will later there was a nock on the door the person who worked at the hotel tolled us that the northern lights were outside. We saw the northern lights outside after and it was amazing.