These munros fall into three subgroups, west of Loch Treig, east of Loch Treig and immediately south of Loch Ossian. The ones bordering Loch Treig are on OS map 41which must be the most useful single map in Scotland for hill climbers.
Loch Treig’s main purpose was to provide a water catchment for the aluminium smelter at Fort William. There is an underground tunnel big enough to drive a double decker bus through to carry Treigs water to the works , the final section appearing as pipes running down the hill to the smelter. The overflow from Loch Treig combines with that from Loch Laggan and has been known to drown the main railway line in the Glen Spean gorge when in winter speight. The water plumes from Laggan dam are a spectacular sight when in full flow.
The same railway which is the main Crianlarich to Fort William line ascends steadily on Treig’s east flank and is a great scenic ride. This railway provides a different way of accessing the hills to the east of Loch Treig. By catching a train to Corrour station you can return over Beinn na Lap, Chno Dearg and Sgriodain to Tulloch Station – a good day. There is also a bunkhouse at Tulloch station in the main station building. You can also take a bike to Corrour and cycle along Loch Ossian, Strath Ossian and out to Moy Bridge and back to Tulloch for those not so good weather days.
Catching a train to Corrour from the north or the south is also the usual way of accessing the two hills to the south of Loch Ossian which is an easy day. The recently restored (to its original 1930s design) Loch Ossian Hostel is a great place to stay during your visit. You can make a longer day of these two hills by following the ridge down south eventually to Rannoch Station and catching the train back. If you do stay at the hostel you no longer have to pump the water from the loch as a daily task and the composting toilets make life that bit sweeter. Don’t forget to try your hand at running round Loch Ossian in under the hour. Corrour Station also has a bunkhouse and last year a very good small restaurant in the main station building for lunch snacks or full evening meals booked in advance (although this may recently have closed.) The latter could be enjoyed as an evening out by train in the two hours wait for the return service. If you have bagged the Ossian munros then the Corbett immediately west of Corrour station is highly recommended.
The hills to the east of Treig can be gained from the minor road to Fersit (which also has a bunkhouse) up a long ridge with good views over Loch Treig with a route back through Coire Lair to connect with the remains of the dismantled tramway for the last part of the return. This construction tramway also ran from the Aluminium works to Treig Dam.
Corrour/ Ossian is on the route of the classic Glen Nevis to Dalwhinnie through route which makes a particularly pleasing cross country ski or ski mountaineering winter route. The Ossian munros would also make a fine winter ski mountaineering day.