This is an aptly named, triangular-shaped mountain lying front and centre on the approach to Arthur’s Pass National Park from Canterbury. It draws trampers across the Waimakariri, to a day trip over The Pyramid and into Sudden Valley for a quintessential Arthur’s Pass tramping experience: steep bush, a thrilling ridgeline, a speedy scree descent and a river bash. 

The trip begins with a brisk crossing of the Hawdon River and then Sudden Valley Stream. At the foot of the south-east spur of The Pyramid is a rock cairn indicating the route through the bush – direct and steep but straightforward and well-travelled. From the bushline there’s a further 200m to the summit (1608m), which lies just 500m away to the north-west.      

From the summit are commanding views of the park’s interior. Mt Wilson (2035m) and Mt Scott (2009m) stand out on the Polar Range to the north-west, and Mt Hunt (1825m) and Mt Valiant (1847m) lie to the north-east.

Continue north along the ridgeline to Pt1565 – care is required to negotiate a high sidle on the exposed east face. Just past Pt1565 lies an excellent scree slope that extends nearly to the Sudden Valley floor. Sudden Valley Stream narrows into a navigable gorge. At one point a chain helps to negotiate a tricky traverse of slippery rocks. There is a brief tracked interlude to avoid Barrier Falls before the valley widens and there’s more river travel to reach the crossing point back at Hawdon River.