The oasis town of Huaccachina is not far from Ica. Many buses only go to Ica, but from there you can easily take a taxi to Huaccachina. The drive to the city surrounded by sand dunes takes only a few minutes.
In the center there is, as you would expect from an oasis, a water surface. You can also go by pedal boat on the water. All around there are several rows of hotels and restaurants. Your will notice that it is a pure tourist city. Nevertheless it is beautiful. You should definitely walk up a sand dune to see the oasis from above.
A sandbuggy and sandboarding tour is definitely fun. It is a bit like a roller coaster. A full day is enough for Huaccachina.