Kawainui Creek is a Class C canyoneering route for Hawaii Standards which meanders from a nice waterfall in the beginning, cuts through a hill to make a small lava tube cave, and provides a few drops just over 100 feet in length. 

The Hamakua Coast has numerous canyoneering routes that offer trips from a couple hours up to a couple days in length.  There are around 20-30 routes through the coast but from the two canyons that we went to visit I found them to be more of rivers with waterfalls than actual canyons.

They are indeed draining a lot of water from above and they had small sections of narrow like passage that could be considered a canyon yet you will find some nice scenery and great waterfalls to rap from when visiting this area.

The waterfalls were beautiful but short lived which is good if you are looking for a short day or looking to grab a few canyons in a day .

We grabbed two short routes during the morning and found some high waters and shady locals that were watching people get out of their cars.This cut our trip into the creek even shorter since we did not want our car to be broken into.

The waterfalls nice and the water is warm which makes the need for a wet suit, a secondary thought but I do recommend checking the weather beforehand to commit your cold threshold.

The anchors were thrashed on the drops so rig naturals or bring a lot of webbing to replace anchors is highly recommended.

I also recommend checking the local water drainage's when visiting any of these canyons since the water can rise at a rapid rate and almost without warning.

Also check for local access updates as we do not want to create a bad reputation within Hawaii by trespassing on private property.