This hot spring is such a hidden gem, you have to add it to your list. You can access it right off the ring road and it is near the town of Akureyri. It is on googlemaps as "secret" waterfall, so follow the directions. It is only a couple minutes off the road. Once parked it is only about a 2 minute walk to the small hot spring river that cascades into the ocean. It has great views of the cruise port in town too. Obviously be very careful here!