Crossing the Tasman river is quite an undertaking. The water is fast and full of silt. You cannot see the bottom to cross, and the rocks are sharp and glacial. We once holed a raft crossing here. It is possible to cross the valley on the Tasman Lake, and Glacier Explorers might ferry one across. Another option is via helicopter. Mt Cook Airport lies directly across valley from the entrance to Gorilla Stream. The flight is short. In September 2020 the cost for a flight in and out of Gorilla Stream was 795$ in total. The helicopter takes 5 people plus gear, so about 80$ per person per flight. Contact Heliworks Mt Cook. There is a wonderful campsite in Gorilla Stream at about 1680m. It is a safe and protected spot in a largely steep and chaotic valley. However the campsite is exposed to a S or SW gale. It was Spring when we were skiing, and the valley had some wonderful soft corn snow. There are several good tours. One was the north facing bowl from the pass at pt 2061. Its a lovely broad slope at about 25 degrees which catches a lot of sun. Over from the pass at pt 2061 we skied south facing slopes into Littles Stream. The slopes are a little steeper at around 32 degrees and offer some wonderful turns. It can be a little trickier getting back out and over the pass again, depending on snow conditions. Take ski crampons at a minimum. There is a wonderful ski tour that connects Gorilla Stream to Pinnacle Stream via a pass at about 2200m. Half the route is in a gully that funnels the large S facing snow slopes above, as well as the west facing slopes on the TL. Hence good stability needs to be ensured. The basin is very shady and held some lovely powder turns. The north face of Mt Little catches the sun and holds excellent corn snow at a constant pitch just over 30 degrees. THE NUNS VEIL The Nuns Veil is the obvious ski tour in Gorilla Stream. The route is south facing and shady. The ski descent would be about 1000m of vertical. We started up the route and made good progress skinning over old avalanche debris. There is exposure to a range of objective hazards for the entire first 500m of vertical. So we moved quickly. At about 2000m elevation we became aware of a lot of graupel in our ski tracks. We stopped and dug a snow pit. We found that we were on a 40cm soft slab. This was sitting on a sliding layer of graupel, about 2cm thick. So the questions became; what will take to release it? An EC shovel test showed that it was not particularly reactive. However when we put this together with the fact that the route is a large debris funnel with very high consequence, we decided to make 2000m our high point, and skied back down. It will be nice to go back and complete this tour sometime. A nice looking loop would be to ski down the east facing gully into Pinnacle Stream, then back over the col into Gorilla Stream… However I would note that the objective hazard risk on the lower half of the Nuns Veil detracts some from the enjoyment of the route..
One more thing to note is that the Burnett Mountains, Liebig and Gammack Ranges are used for heli skiing. Let Alpine Guides Mt Cook know before you head in, and they will graciously give you space.