Mt Aicken is a good introduction to Arthur’s Pass peak bagging east of the highway.
The track to Mt Aicken starts on the same route as the Devil’s Punchbowl falls walk, then turns off steeply to the right. It takes around 5 hours round trip in summer for a normal party, allow 5-8 hours in winter. The labelled summit of Mt Aicken is at 1858m which requires an out-and-back on a tricky ridge 300m along from the high point of 1863m. So treat this last part as optional if you’re keen for a bit more fun scrambling!