Rõuge Suurjärv lies in the deep and picturesque primeval valley of Rõuge, standing as one of the most beautiful and well-known lakes in all of South Estonia. The lake is part of the Rõuge chain of lakes, which are linked together by several streams and springs. Suurjärv is the deepest lake in Estonia, reaching depths of up to 38 metres (according to some measurements, even 41 m). The lake deepens steadily, with its deepest point located slightly southeast of the centre. The bottom is mostly covered with mud, creating a perfect habitat for underwater flora and fauna.

With an area of 13.5 hectares and an average depth of nearly 12 metres, Suurjärv is a flow-through lake. Water flows in from the south from Lakes Liinjärv and Valgjärv, and from the north from Lake Kaussjärv; the outflow is to the northwest via the Rõuge (or Ajo) Stream into Lake Ratasjärv. Numerous shore and bottom springs feed the lake, keeping its waters beautifully clean and cool.

The water color varies from orange to light green, and its transparency depends on the season and light. The flora is diverse – 22 plant species have been found here, including the rare moss species Fissidens julianus, floating pondweed, water lily, and yellow water-lily. Water moss, stoneworts, and spiked water-milfoil cover the lakebed down to a depth of 8 metres. The fish population is dominated by perch and roach, and the lake also provides a habitat for noble crayfish, although the steep depth limits their suitable territory to a small area.

During the summer season, the Rõuge Suurjärv beach awaits visitors with swimming opportunities and a small children's playground, making it a wonderful spot for a family holiday. A parking lot and information boards on the lakeshore introduce the natural values of both the lake and the Rõuge primeval valley. Standing proudly on the shore is also the National Geographic yellow frame – an official photo spot offering a stunning view of the lake and the dramatic slopes of the primeval valley. It is one of the most photographed locations in the entire Võrumaa region.

According to local folklore, Rõuge Suurjärv arrived from the border of Viitina, from the site of the present-day Suursoo bog, carving its way through the hill. Even today, a great valley can be seen in the hill, seemingly confirming this ancient legend. Another legend tells of an old church with silver bells that sank into the lake during a war. Every year before Michaelmas, a mysterious bridge is said to rise across the lake, upon which a black monk walks, chanting:
"The time will come, the time will come, when this church with its bells will rise again!"