Lake Võrtsjärv is the largest inland water body in Estonia. Is located in Central part of the country (58.286560, 26.049585). Is a large (270 km2) shallow polymictic lake with a maximum depth of 6 m and a mean depth of 2.8 m. According to the classification by Lewis (1983) belongs to continuous rather than discontinuous cold polymictic lakes.

Lake Võrtsjärv Buoy was deployed in the summer of 2010 near the deepest point of the lake (N 58.211798, E 26.103163) to gather high resolution data on meteorology and water quality of the lake. YSI EMM 700 bay buoy has been used for float. YSI 6600 V2-4 multisonde (at 1 meter) was fixed at 1 meter depth for underwater measurements. The buoy is equipped with a Vaisala Weather Transmitter WXT520 and a Li-Cor pyranometer (LI-200) for weather parameters. Data collection was controlled with Campbell CR1000 datalogger. System was renewed in 2021. Current underwater measurements are collected with EXO2 multisond and data collection is controlled by Flydog Marine datalogger.