If you're up for a challenging walk, I'd recommend doing the Pinnacles Track, which passes a lookout for these falls (check it out on my map). However, if the intensity of this track is too much, you can still walk to the lookout and catch a glimpse of the impressive Billy Goat Falls.

To get to the lookout, park at the Kauaeranga Valley Road End and follow the Billy Goat Circuit for 600 meters until you reach the lookout. While you don't get very close to the falls (the lookout is a bit far away), you can still enjoy a distant view of the stunning 180-meter-high waterfall.