The Acheron lies in the wide open spaces of inland Marlborough and with road access for all its length it's a good paddle for those who like scenery with their paddling. Most of the river is easy single channel with a few corners, but there are a number of bedrock rapids which require class II and III skills to negotiate. The river is best with flows in the 20-50 cumecs flow range, but it is still a scenic float plus bony rapids run at 15-20 cumecs.
The put in can suit your timetable, but about 25km upriver the river is braided Class I and mostly of interest for bird watchers and fishers. The access is via the Molesworth road via Hanmer Springs and Jacks Pass and access details are available on DoC website. Generally you can get on this road between Christmas and early April, but kayakers can ask DoC Marlborough or DoC Waimakariri for access. The road is OK for cars with reasonable ground clearance.