Selected areas of the park are included into Primeval Beech Forests of the Carpathians UNESCO World Heritage Site.

Meadows, called poloniny in Eastern Slovak dialects, situated on the main ridge of the Bukovské vrchy mountain range are common.

Poloniny National Park contains about 5,981 known species of invertebrates (for example, 91 molluscs, 1,472 true bugs, 819 butterflies, and 403 spiders) and 294 vertebrates.

Besides several mountain trails there is also one connecting outstanding wooden churches from the 18th century in Topoľa, Uličské Krivé, and Ruský Potok.

The primeval beech forests of Havešová, Stužica, and Rožok (all three areas being in the Bukovské vrchy) were designated as a World Heritage Site by the UNESCO on June 28, 2007 because of their comprehensive and undisturbed ecological patterns and processes.