Its summits form part of a long range that feeds several rivers: Ibaizabal, Artibai, Lea, Oka and Deba in Gipuzkoa all of them running to the Bay of Biscay.

Its location in the middle of the province and its height provides great views from the summit, from the nearby sea to the surrounding mountains.

There are still patches of oaks and beeches on the mountain, but the higher zones are covered by huge pastures where sheep, horses, and cows graze.

On February 19, 1985, Iberia Airlines Flight 610 from Madrid to Bilbao hit the antenna and crashed into the north slopes of Oiz, causing the death of all passengers and crew, 148 people overall.

From the road that winds the west side of the massif, where the Viewpoint Bizkaiko Talaia (Balcony of Biscay) is located, conveniently track marked with signs marking the route to Oiz (1,029 m) by Donesolo hill (550 m) ascend toward the pass Arreseburu (798 m) where the chapel of San Cristobal is contact with the runway and the Oiz is made.