Went for a ramble into the Kohala Forest Preserve out of Waimea last week. Normally the trail is a mud slog through the jungle fighting your way to the back rim of Waipio Valley. Half the time we've had to turn back due to rain. The trail's been "closed" since the earthquake a few years back, which damaged some irrigation flumes, but we go anyway.
I don't know if this little waterfall and grotto is named; where the trail crossed the stream it seemed to have a pretty good flow despite the dry conditions, so I thought I'd do a little exploring, walking upstream for a few minutes until I found this.