The canyon is 10 miles long, and up to 3,000 feet deep. That’s Waipoo Falls, ann 800-foot cascading waterfall. It’s a 2-mile cliff hike to get there (I didn’t do it).
Details of the canyon on Wikipedia here (check out their panorama).
“…The canyon has a unique geologic history—it was formed not only by the steady process of erosion, but also by a catastrophic collapse of the volcano that created Kauaʻi.…”