Contrary to its name, Thunder Creek Falls is actually a graceful and narrow 28m waterfall tumbling across the powder blue Haast River. I think it is the most scenic waterfall in the Haast River Valley and Haast Pass area. It is also a very popular waterfall since it has a well-signed car park and a short walk of 5-10 minutes that is wheelchair-accessible. Definitely don't miss out on this one if you're passing through this part of Mt Aspiring National Park.
For more information on this waterfall such as...
maps
directions
detailed descriptions
refer to A Guide to New Zealand Waterfalls (Story Nature Press).