Check out the Rotary Ride, aka Huka Falls Track, for how best to get there.
The trail is intermediate grade 2-3, mostly single track riding and is 10km each way. A note is that the Aratiatia Dam spills water into the rapids three times daily in winter at 10am, 12pm and 2 pm. In summer it also spills at 4pm. Time your ride to catch this. It is defintely cool.
Other return ride options are the Aratiatia True Left Trail linking to Contact Lookout and Wairakei Tourist Tracks. If you can’t be stuffed riding more trails, there is the road back to Huka Falls carpark. The return to town from there is as for Huka Falls Trail. If you reckon you’ve earned it, grab a coffee, or maybe even something stronger.