One place to start is from the Glencullen River valley at around O172204 A. Walk SE along the old bog road into the forest following the Wicklow Way signs until the way emerges from the trees at around O1820 1848 B, a good jumping off point. Leave the way and head SW around 300m to the summit.
Another way to get to the same jumping off point is also from the Wicklow Way, this time starting from the south at the car park around O186168 C.
It's also possible to get to the top on a boggy path from Knocknagun to the west.
Views from the top are fairly unimpeded towards the east coast including Bray. Linkback: https://mountainviews.ie/summit/352/comment/5112/

A Christmas bouquet placed by someone at the foot of the trig pillar on Prince William's Seat: even without memorials, people are remembered in the mountains. I have noticed of late that a noticeable amount of work is being done on all sides of Glencree Valley. A stretch of the Wicklow Way, passing between Prince William's Seat and Raven's Rock is being "upgraded" with a somewhat raised surface of pounded earth and sand, cut by drainage channels at intervals. Further down, on the Curtlestown side, where the way had been all but obliterated by tree felling, this development is welcome, but it isn't altogether obvious why a reasonably valid path higher up needed "improvement". At Cloon, also on the north side of the valley, ample parking space is now provided on both sides of the road, and a wide forestry track takes strollers almost up to Glencree itself. On the south side, the car park at Crone has been greatly widened and a new path has been laid out from close to Ride Rock, overlooking Powerscourt Waterfall, right across the lower forested, north-facing slope of Maulin. The intention would seem to be to improve the recreational value of all these forest areas, which, being so close to Dublin, are popular at weekends and good starting points for more strenuous hillwalks. It's true that the erosion on the adjacent Djouce and Maulin is considerable, but perhaps not all the remedial work that is being undertaken by volunteers is the best. A few months ago, I met a group of people on the path leading up to Maulin from Glensoulan who were assiduously flattening every protruding stone they could find. In the end, the only thing the path will need will be a bit of tarmacadam. Linkback: https://mountainviews.ie/summit/352/comment/2930/

According to the Ordnance Survey this mountain is named after the visit of Prince William in 1821 with his father, the reprobate George IV. To the west is Lugnagun, reached by an unpleasantly eroded and boggy track. Certainly there is a fine view from the top which, as you can see from the picture below, has a trig pillar. The view includes the east of Howth Head, looking over Dublin Bay and Dun Laoghaire. Linkback: https://mountainviews.ie/summit/352/comment/312/

Photo taken from near the summit of Prince William's Seat with Djouce, War Hill, Maulin and Tonduff visible above the misty clouds. Linkback: https://mountainviews.ie/summit/352/comment/3323/