Europe is on fire, in some places such as Greece or Sweden - even literally. Such heat was not experienced in the old continent since... Since when do we measure temperature? I don't know that for sure, but I know that in Iceland we now "enjoy" the coldest summer in a hundred years, as well as the least sunny one since thirty years... And whilst a vision of relaxation in a hot river may not seem very tempting to Europeans at the moment, it was such for us. That is why we opted for the direction Reykyadalur as soon as we could get there! 
This valley is often overlooked by visitors to Iceland, despite the fact that an easy trail leads there from Hveragerði, which is very close to Reykjavík and through which the main route around the island passes. Our short drive there with the new Czarek's Toyota Yaris was enriched by some live Grateful Dead playing from the loudspeaker on Bluetooth. Lazy-style travelling this time!
This day surprised us with exceptionally beautiful weather, so our moods were pretty uplifted because of that matter. By the river, from which the path leading to the valley began, a lot of cars stood. As we found out later, literally a few days before, the route had been reopened by The Environment Agency of Iceland after several weeks of renovation and when valley has been adjusted to 'serve' many human intruders.
The trail takes less than an hour and belongs to the category of pleasant and gentle ones. At the very beginning we were greeted by a small, lost squeals, and further on it was becoming only more picturesque, oneiric, fairy tale-like.
Well, but what exactly is this hot river? As you probably can guess, this is somehow related to geothermal activity of Iceland. And indeed, you're right. Reykjavadalur simply means "Avenue of Steam". The whole area around the river is covered by numerous warm springs, some of which are too hot for swimming. There are also a few "ponds" with boiling mud. Our goal was a river into which geothermal water flows, so it is simply hot and very pleasant to lie in.
Obviously, there had to be something ridiculous about travelling through Iceland, in this case two guys in Scottish tartan costumes ;)
As we ascend higher and higher we pass on our left side a quite deep valley with - obligatory - a waterfall. You can already spot steam at the top of the river, so there is a chance that the waterfall is also warm - but it was not accessible.
Suddenly we come across a bridge and a wall of steam. It looked like a portal to another dimension, after which there is no return. We withheld the air in our lungs and went into this embrace of the sulfur cloud and crossed the threshold to the magical land!
Immediately after getting out of steam, Reykjavadalur emerges in front of us. A wooden footbridge was laid around the river and several wooden curtains were placed, allowing for relatively comfortable changing up your clothes. It doesn't look too invasive and the impression of contact with nature doesn't disappear at all in the place. In the river itself there are a dozen or "seats" composed of stones, so that you can sit comfortably in them. It turned out that it wasn't so crowded and there were still a lot of free spots to relax.
The temperature of such water can be "regulated" in a peculiar manner. Want to get warmer? Go up the river. Too hot? Go a little lower. If you go one way or the other, you can also distance yourself from people if you prefer more privacy.
We found the right place and finally jumped into the warm water! It wasn't hot outside at all and the wind was rather chilly, so the impression was very pleasant - like getting into jacuzzi. When, after some time spent in such water, you get up to take something out of your backpack, you dream of returning as soon as possible to a comfortable place carved in the river.
This place has been visited by the locals for generations, only for a few years now an increased tourist traffic has been seen here. It looks like a rather universal place to relax, whether with your whole family or with friends and a cold beer in hand. The river is quite long and everyone can find something for themselves. I imagine how incredibly awesome it must be to be here in the middle of winter, lying in a hot river, when there is fluffy snow all around you and right above your head you can watch northern lights! After an hour in this angelic valley of Reykjavadalur, we decided to go back. Although it was extremly difficult to get out of it for good, it was devilishly difficult, believe me...
If one of you visits Reykjavík in the coming months, let us know! We will go to Reykjavadalur and make the most original meet-up that no steem front-end has ever seen before!