Trojmezná is so called "two-peak" mountain, the higher peak (1361 m) of which lies at the territory of the CR, while the lower one, known as Bayerischer Plöckenstein (1358 m) is already at the territory of Germany. In vicinity of the mountain top there is probably the best-known point of the border ridge, so called Trojmezí (Three-Borders) - Dreieckmark, where the borders of the Czech Republic, Austria and Germany meet at the altitude of 1321 m. The point is identified with a landmark bearing the names and national emblems of the three countries.
The top of Trojmezná mountain is accessible along the marked mountain-ridge tourist patch from Nové Údolí past Třístoličník mountain. The path then continues to the top of the highest mountain of the Czech part of the Šumava - Plechý.