The Lake Feneketlen (Bottomless) is one of the most popular recreational area of District 11 with a surface area of 1.1 hectars. This artificial lake located between Kosztolányi Dezső Square and Móricz Zsigmond Circus was made at the end of the 19th century.

Previously it was a wetland that failed to interest anybody. The great volume of clay accumulated by the Danube, however, soon attracted attention. At the end of the 18th century a brickyard was established at the site of today’s Kosztolányi Dezső Square and clay was mined from a clay pit nearby. Deepening the pit workers found an underground spring in 1877. Legend has it that water erupted so forcefully that workers had to escape quickly leaving their tools and machines behind. In fact, the brickyard was closed in 1889 and simply groundwater slowly filled up the pit.

The lake remained abandoned until the first decades of the 20th century. What’s more, as if it had been cursed, following the Revolution of 1919 dead bodies were washed ashore several times. Constructions around the lake began when Cistercian monks set up home in Buda in 1912. Architect dr. Gyula Wӓlder designed a building complex with a church, a cloister and a school for them on the shore of the lake. St Imre Church and St Imre High School is still standing there.

The story of the name "bottomless" dates back to this period also. As workers were preparing the construction site for the new buildings in the hillside, they disposed of surplus debris and earth into the lake. However, it did not sink but kept floating, giving rise to the strange belief that the lake might not have a bottom.

Despite the name the lake is just 4 to 5 meters deep, although some sources say that there is a gap at one and with a depth of 18 meters. When springs feeding the lake dried out in the 1980’s water quality started to decline so ventilation and a fountain was installed. Today the lake receives its water from the watershed of the southern slopes of Sas Hill, from rainwater.

Over the last century thickets of cane had surrounded the lake, as well as a barrier and tiny fishing platforms were built around it. The lake and the park around it have become a popular recreational area all day with parents pushing baby strollers, kids feeding ducks, elderly resting on the benches and students having fun after school. Although fish were planted in the lake in the 20th century, nowadays, only few anglers seek their fortunes there. Many unwanted turtles were released in the lake so we often can see them sunbathing along the shore together with ducks.

We can discover several sculptures on the lakeshore and in the neighboring Kosztolányi Dezső Park. Kids definitely favor the Bear standing next to a modern playground and probably thousands of children sitting on its lap have been photographed. The Sculpture of Dezső Kosztolányi in the park is located next to Bartók Béla Street.

Just a few meters from the lake we can see the Park Stage of Újbuda, an open air theatre and concert venue (formerly called Bartók Béla Stage and Park Stage of Buda).

Park Stage of Buda Bartók Stage later renamed to Park Stage of Buda opened in 1958 as an open-air theatre and concert venue seating over 2200 viewers of operettas, varieties and concerts. After 10 years of hiatus it reopened in 2015 under New Buda Park Stage name.

In the summer of 2015, a 520 meters long and 1.25 meters wide synthetic running track around the lake as well as an outdoor gym was finished.