Synthetic Aperture Radar (SAR) map of Ontario Lacus, the largest lake in Titan's southern hemisphere. Radar altimeter tracks show that Ontario lies in a shallow regional basin. The early June 2005 and subsequent June/July 2009 outlines of the lake are shown in cyan and blue, respectively. During the 4-year observation period, the lake receded by about 6 miles (10 km) at places, consistent with an average depth reduction of about 3 feet (1 meter) per year. Inset: Region A with contours of constant distance from shoreline.
Radar Science Team, NASA/JPL/Caltech