Overview
Coomasaharn is a corrie lake, a deep basin gouged out by a glacier, and the largest of six coums strung along the valley southwest of Glenbeigh. It’s about 2km long, dark with peat, and hemmed in on three sides by steep ridges that reflect off the still surface on a calm day. It sits roughly 7km from the village: about 4.5km west on the N70, then 2.5km up a narrow side road. Most people come for one thing, the Coomasaharn Horseshoe, the ridge walk that rings the lake, and if you’re fit for it that’s the reason to make the drive. If you’re not, an hour at the shore is still worth the turn off the Ring of Kerry, and it’s free.
The rock art and the valley’s past
People have walked this valley for a long time: the old pathways here date back around 4,500 years to the Bronze Age. Its real distinction is the rock art. The panels around Coomasaharn, Kealduff and Letter West form one of the richest clusters in the Iveragh Peninsula’s collection of prehistoric carvings – itself the largest concentration in Ireland, holding roughly a third of the island’s recorded rock art. You need to know what you’re looking for, as these are faint cup-and-ring carvings in bare rock, not signposted panels, and they lie on private farmland: view from the road or ask locally rather than striking out across fields. On the northern shore, local tradition places a mass rock where Catholics heard Mass in secret during the Penal era. The naming keeps the older stories too: nearby Seefin is Suí Fhinn, the seat of Fionn Mac Cumhaill, whose Fianna were said to hunt these ridges.
Walking the Coomasaharn Horseshoe
The Horseshoe is a single loop of about 12km, four to five hours, rated moderate, and usually walked anti-clockwise from near the lake outlet. It takes in six summits: Coomreagh (593m), Keamconneragh, also called the Teermoyle Tooth (608m), Teermoyle (760m), Coomacarrea (772m), Meenteog (715m) and Knocknaman (561m). The reward is the outlook from the exposed ridgeline: north to Dingle Bay and the sands of Rossbeigh and Inch, west to the Skellig Coast and Valentia Island, and east to the bulk of the MacGillycuddy’s Reeks.
Two honest warnings. The steepest section crosses the arête between Teermoyle and Coomreagh, and wet rock there is slippery, so it wants careful footing. And Teermoyle’s summit is nearly flat, marked only by a small cairn that’s easy to walk straight past without GPS. The trade-off is solitude: for all its height, this ridge stays quiet, because the Reeks 15km or so to the east pull almost everyone away. That’s the whole appeal.
Water, fishing and dark skies
The lake’s most remarkable resident is its Arctic char: Coomasaharn holds a dwarf form found nowhere else, distinctive enough that some authorities rank it as a species in its own right, the Coomasaharn char. Anglers come for the brown trout, fished from the shore or a small boat. Its sheltered position also suits kayaking and stand-up paddle-boarding, and because it lies on the edge of the gold-tier Kerry Dark Sky Reserve, night paddles are popular here, with the black water doubling the Milky Way back at you. The quiet, rural setting makes it a decent birdwatching spot too, with rare migrants such as Green-winged Teal and Surf Scoter recorded on the water.
Getting there and parking
From the Ring of Kerry (N70), drive about 4.5km west of Glenbeigh and turn left at the Coomasaharn Lake sign. Take the next right at the T-junction and continue 2.5km on a narrow, unmetalled road. A small roadside lay-by serves as the parking area. Space is limited and the road is in constant use by local farmers, so arrive early in summer and always leave room for oncoming traffic.
There are no toilets, shops or information boards at the lake. The nearest public facilities are at Rossbeigh Strand (roughly 5km away) and in Glenbeigh village, which has B&Bs, guesthouses and a few traditional pubs.
Rossbeigh Beach makes a good post-hike stop, with a long stretch of sand, a beach café and safe swimming.
Navigation and seasonal tips
The Horseshoe is well-trodden but not continuously waymarked. The free ActiveME app provides GPS route maps, elevation profiles and stage waypoints, which are worth carrying alongside a physical map and compass. The walk is open year-round, but winter brings snow and ice to the higher cols. Bring waterproof boots, layers and a head torch. The single best call is to start early and go anti-clockwise, since cloud tends to build through the afternoon, and on this ridge it can drop visibility to near zero within minutes.