The Rere Rockslide is a natural phenomenon about 45 kilometres west of Gisborne: a broad sheet of water flows over a smooth basalt rock face for 60 metres before dropping into a deep swimming hole below. People bring boogie boards and rubber mats to slide down — it is genuinely fast and good fun, though you will pick up some bruises if the flow is low.
Nearby Rere Falls is a more conventional waterfall, the largest in the Gisborne region, dropping about 20 metres into a pool surrounded by native bush. Both are reachable by the same road through the Rere Valley, making it easy to combine them in a half-day trip from the city.