This cache is a bit tougher than the others in the Mynydd y Grug series. If you're doing the others in the series too, the best way to this one is to follow the road downhill from Mynydd y Grug 2 (GC6M7QX) until you reach the trailhead at the coordinates given. The route from there down to the actual cache is very steep and can be treacherous when it's wet, so at the very least please take a stick or walking pole to help keep you steady. If in any doubt about your ability to reach the cache safely, TURN BACK. A geocache isn't worth breaking a limb, and remember that you have to climb back up again afterwards. You will need to bring your own pen.
Watch (and listen) out for downhill mountain bikers, as they will find it hard to stop before they hit you if you surprise them on the trail.
The cache is placed in woodland managed by Natural Resources Wales (formerly Forestry Commission Wales) with their permission. See the agreement in the UK Geocaching Policies Wiki.