There are few caches on Whistler Mountain, and even fewer you can get in the winter.
This cache was hidden in the winter and therefore will be easiest to find in the winter. (In the summer you will likely have to climb the tree, which could be very difficult).
You can ski/snowboard right up to the cache, it is within some trees though, so will require a bit of skill to do so, or in the summer you should be able to hike to it.
The cache is zapstrapped to a branch in the tree.