From the car park by the lake take the quiet roads that lead to the Pass through the mountains.  There are wonderful views in all directions especially toward Croagh Patrick to the north west.  Climb 100 metres in less that 0.5 km to reach Drimcoggy summit.  In mist or cloud a compass would be useful.  3 kms across open mountain brings one to the track by the water treatment plant and back to the road.  An alternative route would be to continue toward the north east and join another road which also leads back to the start by a longer route.  This will add 5k to the walk.