The blue-green swamp lake aptly named the Greens in Slovenian.

Zelenci is both the name of a small swamp lake and a natural reserve near Kranjska Gora in Slovenia. It is known for its distinct, gorgeous emerald blue-green water, which is where the name Zelenci, the Greens, comes from.

The lake is fed by several cold freshwater streams, erupting to the surface through layers of marl, a greenish type of calcium carbonate rich mud (you can see the bubbles in the lake if you look closely!). Marl is commonly found as the underlying deposit beneath swamps and marshes, particularly on the sites of former glacial lakes, which is also the case here. The entire Upper Sava Valley was first formed by the Planica glacier and then the Sava river, the longest river of Slovenia, which eventually joins the Danube, Europe’s second largest river. Zelenci are actually one of the two spring sources of Sava, the source of Sava Dolinka, which joins together with Sava Bohinjka from lake Bohinj and becomes just Sava after that.

My boyfriend and I last visited Zelenci in December 2019, on a beautiful sunny winter day. In fact, the day was so nice the photos in this post didn’t need any editing at all (I also never use filters), so the water really is as green as it looks. Like all swamps, Zelenci are also brimming with life, from interesting plant life like the carnivorous sundew, to various animals, particularly amphibians and birds, which is why they’re also a natural reserve. In fact, the whole swamp reserve is quite large, about 47 ha and the Zelenci lake is located at the western edge.

Impressions of Zelenci

The lake area is furnished with wooden walkways and platforms, so you can visit safely without trampling on the local wildlife or sinking into the soggy ground. There’s a small wooden view tower at the end of the walkway with benches and information signs about the lake and its native species, so you can try your eye at bird watching if there aren’t too many people around. However, there’s a snake warning sign right next to the tower, so pay attention when you walk around there during the summer months.

Since the lake never freezes and has a constant temperature of about 6°C, it’s a great spot to visit at any time of the year, which unfortunately makes it a super popular tourist destination. Zelenci have become “the gem of Gorenjska region”, so the spot is quite crowded during the weekends and you’d be better off visiting on weekdays. We got an incoming bus full of Italians during our visit and I’ll tell you honestly that the area is too small for that.

If you want to escape the crowds, you can wander a bit further into the woods leading to Zelenci, which is exactly what we did. There’s a signposted forest path leading to Rateče and Planica from there, but we stopped at the first open field next to Zelenci and had a small picnic by the lazy river in the sun and snow.

The woods nearby

We noticed hundreds of small spiders running around the half-submerged twigs and leaves on the river banks, trying to catch the little insects flying just above the water. I have a rather odd relationship with spiders: I find them fascinating to observe in their natural environment, but freak out like a bimbo if certain creepy legged species of spiders (looking at you, daddy-longlegs) wander into my space (house, tent or, heaven forbid, a sleeping bag) and then need to mentally prepare myself to take them out. Given that, these little guys were quite interesting to observe, although I had to ask my boyfriend to take the close-up photos, because I was afraid I’d drop my phone in the water if a spider suddenly moved or jumped. 🙂

Water spiders

Getting there: Zelenci are located about 5 minutes walk through the woods from the main road, right after the Podkoren village. The walk is super short and easy, but the path can be covered in ice during the winter. There’s a small parking lot with trash cans, so don’t toss your waste out in nature, but there were no operational toilets when we were there (location on Google Maps here). Visiting Zelenci and parking there is free and mostly people only stay a short time, but finding a parking spot can be difficult during peak times.

The other option is visiting by bike or on foot following one of the walking paths through the woods from Kranjska Gora or Rateče. Most people come to the region because of the Kranjska Gora skiing centre, but there’s a large number of nearby sights you could combine your visit to Zelenci with: the Martuljek waterfalls, the Vrata (door) valley, the village of Mojstrana and Peričnik waterfall, one of the 5 most beautiful waterfalls in Slovenia, lake Jasna, Planica and the Tamar valley or Vršič pass with the Russian chapel a bit further away (often closed in winter due to road conditions, check online before you go). Alternatively, you could also hike to Tromeja, the 1508 m high peak at the triple border of Austria, Slovenia and Italy.