At a glance
Llyn Bochlwyd (LL57 3LZ) — a high mountain lake at 600 m between Tryfan and the Glyderau, 30 minutes steep ascent from Ogwen Cottage on the A5. Wild swimming for experienced hill walkers only (very cold · steep access · 600 m altitude). Snowdon Sherpa S6 bus. Free.
About Llyn Bochlwyd
Llyn Bochlwyd (Grey-Cheeked Lake) occupies a cwm between Tryfan's east face and the rocky buttresses of Glyder Fach at 600 m — significantly higher and more exposed than the more accessible Llyn Idwal in the next cwm to the west. A steep, rocky path from Ogwen Cottage on the A5 gains 200 m in under a mile, bringing walkers abruptly into a world of rock and dark water enclosed on three sides by mountain cliffs. On most days the lake is deserted — the main walking traffic in the Ogwen area goes to Cwm Idwal and Tryfan, passing the Bochlwyd cwm at a distance.
For wild swimmers willing to make the steep approach, the lake offers one of the most dramatic settings in the Ogwen Valley. The water is cold — colder than the lower lakes, fed from the frost-shattered terrain of the Glyderau plateau above — and the rocky cwm walls enclose the swimmer in a setting of complete mountain character. The Bristly Ridge scrambling route to Glyder Fach begins at the lake's western end, making it a natural staging point for harder mountain days.
Safety information
Wild swimming carries serious risks. Never swim alone. Tell someone where you're going and when you'll be back. Enter the water gradually to avoid cold-water shock. Know your exit point before you start. Wear a tow float and consider a wetsuit even in summer — Welsh lake and sea temperatures rarely exceed 16°C.
In an emergency call 999 and ask for the Coastguard (sea) or Police / Mountain Rescue (lakes & rivers). Nearest A&E: Ysbyty Gwynedd, Penrhosgarnedd, Bangor LL57 2PW. Tel: 01248 384 384.
Find it on the map
Frequently asked questions
Llyn Bochlwyd is reached via a steep path from the A5 road near Ogwen Cottage (LL57 3LZ). From the Ogwen Cottage car park (pay & display), follow the Tryfan South Ridge path or the Bristly Ridge approach towards the lake — the path climbs steeply south over rough terrain from the Milestone Buttress area of Tryfan, gaining approximately 200 m in height over a short distance (less than 1 mile). The ascent takes approximately 25–35 minutes and is steep and rocky throughout — good footwear is essential. The Snowdon Sherpa bus S6 serves Ogwen Cottage from Bethesda and Llanberis. Llyn Bochlwyd is at the same level as the start of the Bristly Ridge approach to Glyder Fach.
Llyn Bochlwyd is a serious mountain lake at 600 m — one of the highest accessible wild swimming lakes in North Wales. The water is very cold (significantly colder than lower lakes), the terrain to reach it is steep and rough, and the position between Tryfan and the Glyderau plateau means it is exposed to rapid weather changes. It is suitable for experienced wild swimmers and hill walkers only — not for beginners or those unfamiliar with mountain environments. The lake is less visited than Llyn Idwal (accessible via a gentler path), which means the Bochlwyd cwm retains a quiet, remote character. Standard mountain swimming rules apply strictly: never alone, tell someone your plan, enter slowly, know your exit. Nearest A&E: Ysbyty Gwynedd, Bangor LL57 2PW, tel: 01248 384384.
The lake sits in a rocky cwm between the east face of Tryfan and the rocky buttresses of Glyder Fach — the view from the lakeshore is dominated by mountain architecture. Tryfan's distinctive twin summits (Adam and Eve) are visible above and to the left; the rock walls of the Glyderau rise above the far shore. Looking back (north-east) down the cwm, the Ogwen Valley is visible below with Llyn Ogwen gleaming on the valley floor, and the great bulk of the Carneddau beyond. It is a view entirely enclosed by mountain rock — there is no sky to the south, west, or east, only cliff and ridge. The lake's dark, cold water reflects the encircling grey mountains on still days.
Yes — Llyn Bochlwyd is the starting point for the Bristly Ridge route up Glyder Fach (994 m), one of the classic scrambling routes in Snowdonia. From the lake, the ridge to the right (west) ascends steeply over rocky ground and then via Bristly Ridge — a Grade 1 scramble requiring the use of hands. From Glyder Fach, the Glyderau plateau extends to Glyder Fawr (1,001 m) and then descends via Y Garn or the Devil's Kitchen to return to Ogwen. This is a serious mountain day, suitable only for experienced walkers and scramblers with appropriate equipment. The Glyderau page on this site gives full detail of the routes. For wild swimmers who are not continuing to the summit, the lake itself and the immediate cwm give a rewarding experience in 2 hours.
Ogwen Cottage (LL57 3LZ) on the A5 is the access point — a mountain hut and outdoor education centre with a small café (seasonal opening), toilets, and the main car parks for the Ogwen Valley. It is the start of both the Cwm Idwal NNR path (to Llyn Idwal) and the mountain paths towards Tryfan, the Glyderau, and Llyn Bochlwyd. The valley has no village or facilities beyond Ogwen Cottage — visitors should bring food and water. The Snowdon Sherpa bus S6 serves Ogwen Cottage, making the area accessible without a car (the bus runs from Bethesda to the west, and from Nant Peris connecting to the Llanberis-area services).