Clamber up a rugged valley to a two-bunk hut with beautiful mountain views.

The name ‘Sudden Valley’ is enticing, suggesting a place where you can expect the unexpected. The trip to the two-bunk hut can be challenging, but is well worth the effort.

The route starts at Hawdon Shelter. Follow the Hawdon Hut Track for about 500m before crossing the Hawdon River. If the river is difficult to cross (more than mid-thigh) the many crossings of Sudden Valley Stream will be very difficult.

Head northwest up the true right of the riverbed to where Sudden Valley Stream emerges from the hills.

A sign indicates the way to the bivvy, but after that the route is unmarked. Head up the open streambed for a couple of kilometres until the valley narrows. Multiple bouldery crossings require concentration as the stream becomes steeper and the channels become narrower.

After about a kilometre into the gorge, look for a very steep scree slope on your right that may be marked with a cairn if movement of the scree hasn’t taken it out. If you miss this and keep going upstream your way will be blocked by the appropriately named Barrier Falls.

Flooding in the spring of 2025 has made this scree slope unstable. Crawl your way up for about 100 vertical metres and make sure you don’t miss a large orange triangle on your left that marks a sidle track into the bush. (The route up the scree and into the bush is marked as a track on some maps, including Topo Map.)

From the top of the scree, a narrow, steep ground trail sidles through beech forest and rejoins the stream just beyond the top of Barrier Falls. Take note of this point as the track entrance is not obvious on the return. From here, there’s more slippery boulder hopping and stream crossings for another 1.5km before the valley opens up and you reach river flats with views of mountains all around.

Continue up the valley for about 2km then look out for Sudden Valley Biv tucked into the beech trees on your left (the true right).

It’s a comfortable two-bunk hut built in 2007 to replace an old crawl-in bivvy on the same site, one of four such bivvy replacements in Arthur’s Pass National Park that year. The hut book shows some visitors have arrived via interesting routes and long days over the Polar Range from the Edwards Valley, or from Hawdon Hut. Further up the valley would be a spectacular place in winter or spring with the mountains covered in snow.

Return the same way, making sure to pick up the track that bypasses Barrier Falls.