The Grojogan Sewu waterfall is one of the more spectacular of Central Java. The falls are on the southern side of Mount Lewu, more or less opposite to the Sukuh and Ceto temples. It's a popular destination for the locals, and seems to have been developed with them in mind. Despite the spectacular natural beauty of the falls, several western style swimming pools, and even an entire water park, have been built into the landscape around the base of the falls. Still, it is a pretty spot and the falls are beautiful.
Admission to the falls is 19,000 Rupiah (1.14 USD).