One of the most evocative Sardinian forests, Montarbu occupies 2800 hectares of territory, a small part of which is in Ussassai and most of which is in Seui, to the east of the town located ten kilometres away. The state-owned forest stands out on the slopes of Monte Arbu and Tonneri. To the north, the Flumendosa river separates it from Gennargentu. In the centre, there is a plateau, at a height of approximately one thousand metres, with vertical walls and valleys furrowed by streams, among which you will be impressed by the rivulet of Rio Ermoliosu, with its colours and numerous springs that sometimes form waterfalls in the greenery, like that of Serra Middai. The summit is Punta Margiani Pubusa: it is at an altitude of over 1300 metres and offers spectacular views. Descending from the peak, after having come across the spectacular 'ponor' of Su Stampu and Su Turrunu, you will encounter S'arcu and Pirastu Trottu from which you will reach the limestone 'butte' of Perda Liana, a unique natural monument.