Seljavallalaug is one of the oldest swimming pools in Iceland built around 1923 to teach kids to swim. Although it's man made, you could say it's "natural" because the water comes from a geothermal source and therefore it does not require any additional heating.
If you are travelling from Reykjavik, you'll have to drive the Ring Road to the south until you're just past Þorvaldseyri ( a museum). There is a sign that says Seljavellir and if you follow the road until it ends (the last strech is not paved), then you are in the right place. I drove there in a Toyota Avensis so this road should be accessible for all cars. I advise you to drive carefully as there could be some big rocks on the gravel road. The parking space is next to the new pool where there are two houses and a big parking lot. You're not going to the new pool, though – the "old pool" is going to be today's mission. To reach the "old pool", you have to walk into the valley for approximately 20 minutes.
The walk to the pool was rather easy and everyone should be able to walk it without any difficulties. When I walked there the first time I took the straight path and went over a stream and some rocks but when I came back I noticed there was a much better path up next to the mountain without any rocks and much smoother. There was one stream on the way with a partial bridge but also a few rocks that you had to climb over.
As there are a few rocks that you might have to step on, I recommend wearing good shoes. I met one man who was wearing sandals, proving that you really don't need hiking boots or anything of that sort, the path is actually quite good. The walk also doesn’t take too long, roughly 15-20 minutes, depending on whether you're stopping and and looking around on the way. I stopped to take pictures and enjoy the view but still the hike only took me around 15 minutes.
As you can see, the swimming pool is hidden behind these mountain walls so it isn't visible from the parking lot and the way is pretty straight forward.
I went to the swimming pool around midnight and got enjoy the midnight sun. There where also not many people in the pool around that time.
When you reach the swimming pool, there is a small house where you can change your clothes and leave them inside to keep dry, but the floor is very dirty and can be wet. There are no showers there so don’t forget to bring a towel!
Most of the time, the pool is quite full of algae and when I went, the pool floor was covered in it but that didn’t stop me from enjoying it!
As it wasn’t cold outside when I got there the water wasn’t too warm but somewhere around 77 degrees (25 degrees on the Celsius scale). There are also two places in the swimming pool where the hot water enters the pool, both by the rocks where the water is flowing and in the left corner at the deep end. Be careful if you feel like climbing about up to the rocks as they are very sharp and you can hurt yourself if you aren’t careful.
One traveler that was swimming when I got there had this unicorn floater that I thought was both really funny but also very clever! If you want to get closer to the hot water source at the deep end of the pool, but you don’t feel like swimming or holding onto the wall on the edge of the swimming pool, it can be very relaxing and comfortable to have something to float around in.
The unicorn float. Wonderguide/Ingthor.
There are no shops or supermarkets close by, so I recommend if you are taking a trip to Seljavallalaug, that you bring something with you. Since there are no trashcans either, you'll have to carry the trash back with you (please don’t leave any trash behind!).