Forest Lagoon

You float in one of two geothermal pools cut into the Vaðlaskógur hillside, with spruce and birch around you and Akureyri spread along the far side of Eyjafjörður. The larger pool covers about 530 square meters and the smaller about 330, and the operator holds both at 37°C, which is warm enough for a long, slow soak rather than a quick hot dunk. Next to the dry sauna there is a cold pool at about 11°C.

Entry starts at 7,490 ISK, and the Calm and Delight packages add a towel and one or two drinks; children 5 and under are free, and only Icelandic krónur are accepted. It is a five-minute drive from town, so you can come straight from dinner and stay until the late closing. Shower without a swimsuit before you go in.

The honest downside is that this is a modern spa with a fixed, moderate water temperature; if you want something wild or very hot you will find it cooler than expected, and it closes for maintenance days, so check before driving over.