Thanks to its size, the Crater travertine lake is regarded as the largest travertine lake not only in Slovakia but also in Central Europe. Moreover, Slovakia has no other water-filled travertine crater with such a significantly defined boundary wall similar to that in the Vyšné Ružbachy Spa, situated at the foot of the Spišská Magura hill. Since 1967, this unique natural feature is included in the list of protected natural sites of Slovakia.
The name and the shape of the Crater evoke volcanic origin or maybe a result of a fallen meteorite. However, the shape of the Crater as we know it today was actually formed by depositions of travertine brought by the out-flowing mineral water. This had created a travertine pile that collapsed over time. The collapsed pit was then filled with mineral water. Its shape is more-less circular with a diameter of approximately 20 meters. The total surface area of the Crater in Vyšné Ružbachy is approximately 300 square meters. The lake is about 3 meters deep. The spring emerges in the middle of a travertine pile, in a depth of approximately 4 metres. In 1958, the drill hole was cleansed and deepened to 9 meters; this increased the inflow rate to as much as 8 l/s. The lake is bordered with a wall approximately 1 or 2 meters high. An interesting fact is that the wall has a notable stone ring around its internal perimeter.
Voda z Belianskych Tatier
Voda v jazierku pochádza až z Belianskych Tatier. Belianske Tatry sú geologicky tvorené vápencom a dolomitom, čím sú nápadite odlišné od susediacich, žulových Vysokých Tatier. A práve tu, v panenských horách, kvôli prítomnosti vápencov a dolomitov voda v podzemí mineralizuje. Následne putuje smerom na východ pod súvrstviami flyša Spišskej Magury. Vďaka tektonickému zlomu, na ktorom ležia Vyšné Ružbachy, táto krasová voda pod tlakom následne vyviera na tomto mieste na povrch. Počas bezveterných dní je úžasný pohľad na dno, cez úplne priezračnú, kryštálovo čistú vodu.
A mystical place in the spa
A temperature of water in the lake is approximately 23 °C and the water is strongly mineralised (as much as 3.13 g/l of water). The temperature is approximately the same all year round, with only a 2-degree variance. This means that it does not freeze in winter, and in summer it provides pleasant refreshment. On winter days, dense steam rises up from the lake and the whole Crater turns into a mystical site, reminiscent of volcanic geysers found in northern countries. The travertine lake is filled with water from the spring, enriched with carbon dioxide gases penetrating through the cracks on the bottom. Water then flows away via a stream down the hill and creates a beautiful waterfall where the terrain breaks.
In 2022 (and previously in 2015 and 2009), the Vyšné Ružbachy Spa in cooperation with the Vyšné Ružbachy Municipality Office and the local fire brigade drained and cleaned the Crater from mud sediments and repaired the drainage system. The drainage carried out in 2015 was preceded by a failure on the pipe that drains this thermal mineral water out of the Crater. Pumping water out of the Crater took a whole day as it was necessary to consider the effects on the surrounding biotope and on the stream into which the water flows from the Crater. Cleaning the Crater is always associated with excitement about a chance of finding lost treasures, which has happened in the past. Jewels and coins are not rare to find.