The legend of Sangkuriang explains how Lake Bandung and the mountains surrounding it were formed. Now, this is quite a legend, so pay attention!

Magical princess Sumbi, blessed with eternal youth, is born from the union of a king and a wild boar who was magically turned human. The king was aware she was a boar when he married her. After Sumbi is born, her mother reverts back to being a wild boar. When she grows up, the beautiful princess unknowingly marries her dog Tumang (also magically transformed into a human) and has a son, Sangkuriang. Tumang also reverts to his animal form after his son is born. One day while hunting with Tumang (his dad), Sangkuriang becomes angry when the dog (his dad) chases a wild boar (because he believes the boar is likely his grandmother). He kills the dog (his dad) and slaughters it for its meat (we did mention that it was his dad, right?). When his mom Sumbi finds out, she attacks Sangkuriang with an ax, splitting his head open. Sumbi forces Sangkuriang to leave home, and they are separated for 20 years. When he returns as a man, Sangkuriang falls in love with his mother (remember, she is eternally young) and they become engaged. Obviously, they do not recognize one another. One day while massaging his head, Sumbi discovers the wound and realizes that he is her son. She tells him, but he refuses to believe her and insists on going through with the wedding. She agrees, but only if he can fulfill a seemingly impossible task. He must build an entire lake in a single night. Sangkuriang gathers materials and gets to work. When he is almost finished ahead of schedule, Sumbi panics, and uses magic to make the sun rise early. Obviously, she desperately wants to insure that her son/fiance will fail in his task. In his anger at failure, Sangkuriang tosses around some debris and building materials, thus creating several mountains. Of course, he had basically already formed the lake.

In the film version (which starred Suzanna, as Sumbi) there are a few revisions/variations. Sumbi is already an adult when the film starts, so we don't see all the boar transformation stuff. The marriage to the dog is told in flashback. Also, Sangkuriang shoots the dog by mistake in the film, and realizes that he really is his father -- but he slaughters him anyway!!! It's no wonder mom took an ax to him.