Quick answer
Durmitor's headline activities are the Black Lake circuit, the climb to Bobotov Kuk at 2,523 metres, the Durmitor Ring drive and rafting the Tara Canyon — all covered by one 5 EUR conservation fee, per person, per day. The park gates keep the same hours every day of the week, 07:00–20:00, and the 07:00–09:00 window buys quiet trails and cleaner light.
Durmitor was shaped by ice, not water alone. Eighteen glacial lakes sit in its cirques, known locally as gorske oči, the mountain eyes. The largest, Crno jezero, lies a short walk from Žabljak's edge and is where most visitors begin. Any honest list of Durmitor National Park things to do starts there and then spreads outward across roughly 390 square kilometres of limestone plateau, beech forest and pasture. UNESCO inscribed the massif in 1980, together with the Tara River Canyon that forms its northern boundary.
The park is not a single site but a dispersed set of them, and that shapes every plan. Nacionalni park Durmitor spreads across a plateau ringed by dozens of peaks above 2,000 metres. Activity falls into three tiers. At the gentlest, the Black Lake shoreline loop and the marked paths through the black pine stands of Crna Poda ask for little more than good shoes. In the middle sit the day hikes: Ledena pećina, the ice cave under Obla Glava, the Škrčka lakes below their limestone amphitheatre, and the chairlift-assisted approach to Savin Kuk. At the top is Bobotov Kuk, 2,523 metres, usually attempted from Sedlo Pass and treated as a full day.
Beyond the massif, the Tara River Canyon does the heavy lifting. It cuts roughly 1,300 metres deep, the deepest in Europe, and carries the rafting sections that many travellers arrange before they arrive. The Đurđevića Tara Bridge spans it in five arches. Nevidio, the slot canyon on the Komarnica, is guided only. Drivers use the Durmitor Ring, the circular road over Sedlo, which turns the park's western flank into a sequence of viewpoints rather than a destination.
What to do with all of this is a question of sequencing. Most itineraries base themselves in Žabljak and radiate outward, pairing one high objective with one low one each day. Weather on the plateau changes fast, even in August, so flexible ordering matters more than ambition. Anyone building a shortlist of Durmitor National Park things to do should decide first whether the trip is a walking holiday, a driving one or a water one — the answer changes which northern Montenegro landmarks deserve the detour, and whether a guided Durmitor National Park tour is the practical route to Nevidio and the Tara.