The three glens Isla, Prosen and Clova meet at the top of the Mayar, at 928m one of two Munros at the head of the glen, the other being the Driesh (947m).
 
It is a highland environment, save for the lowest farms on Pearsie & Cortachy.
The head of this glen, like the others, is heather moorland occupied by red and black grouse, a few ptarmigan and wild cat, red deer, mountain hares, and farm sheep and cattle. In medieval times Glenprosen was a baronial deer forest and for the first half of the 19th Century it was still a world class grouse moor. However much of the land between 350 and 550m was planted with Spruce by the Forestry Commission in the early 1960's.

Lower down, the Glen is perhaps more wooded than its neighbours, with large expanses of native birch hugging the slopes around grass pasture; and most of the length of the Prosen river is lined with natural alder. There are a few coniferous plantations here too, but much smaller in scale, and adding a patchwork appearance to the landscape.

And lower still, the lower reaches of the river, from Lednathie down, Pearsie and Cortachy are good for salmon fishing, above that the fish tend to come only towards the end of the season, in September.