Aran Benllyn and Aran Fawddwy from Llanuwchllyn

This is an out-and-back from the small car park at Llanuwchllyn beside the Afon Twrch, and the stored figure of 13.5 miles / 21.8 km is the full there-and-back day (the mapped corridor is 10.79 km one way). You start on a track out of the valley, pick up a bridleway and path climbing toward the crest, then work along the high ground over Aran Benllyn and the broad rocky shoulder of Erw y Ddafad-ddu to the 905 m summit of Aran Fawddwy. The return uses the same ground, so you get the ridge twice.

Allow roughly 7 to 10 hours. Some guides quote nearer seven, others closer to ten and a slightly longer distance depending on where you trace the line and start, but plan for a full mountain day rather than a half day. The climb is sustained from about 194 m in the valley to the 905 m top, and the ridge undulates, so you gain and lose height repeatedly on the way out and again on the way back. This is a serious hill walk that needs fitness, map skills and proper footwear.

Expect rocky sections, boggy patches, stiles and a fence line to follow in places, along with occasional easy scrambling. The ridge has steep drops on one side, so keep children and anyone nervous of edges well away from the crest. Wayfinding is poor in stretches and the paths are not always obvious, so carry a map and compass or GPS and know how to use them. In cloud the whole outing becomes considerably more serious.

The payoff is the long, quiet high ridge and the wide view: Llyn Tegid below to the north, Arenig Fawr, Cader Idris, Barmouth Bay and the broader spread of Eryri's mountains. Summit ground is a mix of rock and grass, which makes good foreground. Go on a day with clear visibility, since the best pictures here come from the rocky ridge line and summit shapes set against distant peaks and the lake, and low cloud simply removes the reason you came.

Settled, clear spells are what you want, whatever the season. Wet weather makes the boggy sections heavier and the rock greasier, and the ridge is exposed to wind with nowhere to shelter. Compared with the famous northern Eryri summits this is lightly travelled, so you may see very few people, though that is not a guarantee of having it to yourself.

The start is the small car park by the Afon Twrch, reached through Llanuwchllyn village off the B4403. Spaces are limited, so arrive early on fine weekends, and there is no toilet facility to rely on here. Access arrangements in the park link existing access rights on Aran Benllyn and Aran Fawddwy. Dogs are allowed on public footpaths and open-access land: keep them under close control, use a short lead near livestock or wildlife, and use a lead no longer than 2 m on open-access land between 1 March and 31 July.

It is a long, committing walk with the same ground covered twice, and the reward is entirely dependent on visibility. If you mainly want Aran Fawddwy itself and a shorter day, the approach from Cwm Cywarch is a different and briefer outing, but it misses the Aran Benllyn ridge that makes this route worth the effort.