Forestry car park about 1/2 mile up the road from the entrance to Castell Coch, at Tongwuynlais,just outside Cardiff - (called Fforest Fawr). Daytimes, mainly gay guys, but some couples in cars or go into the woods and happy to be watched. Gates are locked in evenings, but once in the car park, you can get out even when gates are locked. Go into informal paths from car park into woods, below the main path.