Fantail Falls is on the northern side of the Haast Pass / Tioripatea high point and has long been a very popular stop on State Highway 6. It is well signposted with a large car park just off the side of the road. Then it is just a two minute walk to the edge of the gravel beds of the Haast River, directly opposite the falls.
When it rains heavily, getting over to the falls is definitely a wet exercise, but you can walk most of the way across staying dry once the river drops. In these pics, it is hard to see the fantail, because of the torrent of water, but it is much more obvious on a nice summer day.
The Brewster Track also starts from the car park. Note that this is a reasonably tough 2 to 3 hour (1 way) 1,000 metre climb to 1400 metres on a mostly rough forest tramping track up the side of Mt Armstrong to the Brewster Hut. You start with feet wet as well as the entrance is on the other side of the river. It is worth it if you want more of an adventure and have plenty of time. From the hut, you can also get access to the Brewster Glacier to the northeast.