Beinn Challuim is a Scottish mountain located in the very northern part of the Loch Lomond and the Trossachs National Park six kilometres east northeast of the village of Tyndrum in the Stirling Council area. The mountain stands in the Forest of Mamlorn, an ancient deer forest in Breadalbane.
With a height of 1025 metres (3363 feet) Ben Challuim qualifies as a Munro and a Marilyn. It stands at the head of Glen Lochay and is a prominent peak when seen from the head of that glen, its western slopes dominate the north eastern side of Strath Fillan. When seen from the south the summit of the mountain cannot be seen, being hidden behind the south top. The mountain name was originally written as Beinn Challuim before Ben Challum became the norm. However in recent years the Ordnance Survey have reverted to using the original name on their maps.
Beinn Challuim is often regarded as a smooth grassy hill mainly because these are the characteristics of the southern and western slopes which are seen by many people from the A82 road around Strath Fillan. However from the north it shows a more exciting form with a steep and rocky face overlooking the head of Glen Lochay. Beinn Challuim is made up of three ridges, the broad grassy south west ridge descends to Strath Fillan and is used in ascents from there. The north west ridge is steep and rocky and descends to the Bealach Ghlas-Leathaid (575 metres) and then connects to the Corbett of Cam Chreag. Another ridge goes easterly, descending into Glen Lochay.