Be sure to visit the Blue Lagoon — a spa, but also, a whole other world, really. One can easily spend a day rejuvenating with a number of special treatments, enjoy the lovely dining, and of course, nature. One can learn about the wonders of geothermal seawater, lava fields nearby, and more.
Spend the afternoon enjoy Lake Mälaren—located in the countryside, just west of Stockholm, and is the perfect spot to visit, itinerary left behind, for an afternoon [or perhaps, day or two] of exploration and discovery, and if you wish, a refreshing swim!