The lake has an area of. The lake has an averagedepth of and a maximum depth of. It is long, and its shoreline measures. It has a volume of.
History
Lake Niinsaare used to be a closed lake. In 1963, a ditch was dug in Lake Mustjärv from Lake Suurjärv, which caused the water level in Lake Niinsaare to drop significantly. By the summer of1968, at least 50% of the lake was dry.