This is a hill isolated by roads and properties and makes for a short though somewhat rough up and down walk. Walking in a dry period would be preferable though not essential.
One place to start is from the road near Lough Acoose on which there is a small amount of parking. Find a way onto the hillside such as the animal track at V7544285617 A. Access may also be possible from the B&Bs around V7718 8743 B
There is a spot height of 228 on a rocky bump and either side is equally good or bad. Generally, follow the east edge of the forestry plantations, using the numerous sheep tracks as there is no walking path through the occasionally dense furze. The top is around 1200m away which will take aournd 40 mins to reach and about 30 to return.
Note that the apparent minor road on the OS map leading north from L. Acoose is in reality a forest track festooned with an Ireland of the Unwelcomes sign.
The rewards for such a small hill are considerable. There is a huge view of the Reeks, the Iveragh penisula and even parts of Dingle. Linkback: https://mountainviews.ie/summit/899/comment/5658/

It's hard to do justice with the extent of the view in any photograph, particularly from a dull day, of the enormous 220 degree panorama that Knocknabrone enjoys, but we can at least have some fun with it.

MountainViews presents the impressionist version of the Iveragh peninsula from Reeks to the left and Seefin of the Glenbeigh Horseshoe on the right. Added bonus feature: Sky Angst Linkback: https://mountainviews.ie/summit/899/comment/6750/

Derryfanga despite being a low hill can offer magnificent views to Dingle Bay and Peninsula, a view not too much different from the bigger hills of the adjacent Reeks area. Good weather provided, you can also see all the peaks of Coomloughra horseshoe (Caher Tops, Carrauntuohil, Beenkeragh, Skregmore etc.) as well as the route up to Caher West Top. Particularly nice to be seen from there is Skregbeg, though I have no photo of it. My son and myself coming all the way from Germany went "up" Derryfanga on 3rd and 4th of September, 2005 while staying at Sheila Doona's Lakeview B&B near Lough Acoose. From there it takes only 10 to 15 minutes to reach the top. So in case you miss the high peaks due to bad weather, but have some short period of good weather on that same day it is rewarding to take the short walk up Derryfanga. Linkback: https://mountainviews.ie/summit/899/comment/3466/