Bundek is an artificial lake situated north from Zaprudje and Sredisce neighbourhoods. It was made since this was the place where they used to take gravel that was put in hundreds of thousands of tons of Novi Zagreb's concrete walls and roads.
First it was known only as Jezero (The Lake), and it was very popular for swimming and sunbathing in 1960s and 1970s. Although the beaches were regulated, and even had safeguards, some people also drowned here. It was later named Bundek, which was the surname of the little boy who was the first victim of the lake.
In the mid-1980s Zagreb became jealous of Novi Zagreb and they decided to invest a lot in the making of Jarun lake, on the other side of Sava. (Well, this is my version of the story, anyway). So Jarun became a popular spot for sports and nightlife, and Bundek became neglected.
Occasionally there are actions when citizens of Novi Zagreb are participating in cleaning of the lake. Only few people will swim in Bundek now, but it’s a nice place for sunbathing, fishing, making grill-picnic or simply to walk around the lake.
(Note that in the evenings area is popular among the gay population of Zagreb - not of any danger, just a warning).