The highest mountain of the Czech part of the Šumava (1378 m) lies at the state border between the Czech Republic and Austria. It is formed of a distinct group of granite rocks and boulders rising over the glacier lake Plešné. In the slope beyond the lake, about 1,5 km distant from the mountain peak, at the altitude of 1311 m and in a hardly accessible place, there is a 14,5 m high monument (obelisk) to the Šumava writer and poet Adalbert Stifter, built here, where he liked to look into the countryside from, by local stone-cutters.
On the southern slope of Plechý a corrie of 211 metres rises above Plešné Lake. It is a significant geomorphological formation representing one of the most precious parts of the local Natural Reserve. Nearby the "dam" (cirque or corrie) of Plešné Lake there is an extensive stone sea formed of huge, frost-weathered boulders of coarse-grain Plöckenstein granite. The Schwarzenberg Floating Canal passes across the northern slope of Plechý.