The route starts from near Llyn Ogwen (Tal y Llyn Ogwen farm) where a footpath leads you directly up northwards. The start is really steep and with excellent views of Ogwen valley and Tryfan in the background. At about 600 meters the track leads to Ffynnon Lloer reservoir (660 m) and then left (west) up to Pen yr Ole Wen. The trail remains to be steep with some sections of easy scrambling (see the route's primary image), until you reach the summit of Pen yr Ole Wen with exceptional views of Northwestern Wales and the Isle of Anglesey. From there, an obvious trail leads northwards with passing over Carnedd Dafydd (with 1044 metres being the second highest peak in the area) and over the ridge of Ysgolion Duon until the summit of Carnedd Llewelyn. The trail stays above 900 m / 3000 ft from Pen yr Ole Wen until Carnedd Llewelyn.
In the summer season normal hiking gear + map & compass or GPS is fine. Keep in mind that in Welsh mountains the weather can change rapidly and take some warmer & waterproof clothes.
"It occurred to me that anyway one more Sunday was over, that Maman was buried now, that I was going back to work, and that, really, nothing had changed."
--Meursault in 'The Stranger'