This is one of many attempts to get the long exposure water effect right on a waterfall. It was taken pretty early on during our trek down the road to Hana (and, yes, it really is about the journey and not the destination).
Although this is perhaps the least impressive of the waterfalls we saw, I think it is the one where the effect worked best. We actually did the trip as a loop, going past the seven sacred pools and back past the Tedeschi Vineyards.
The road for the first hour or so past the seven pools was partially unpaved (by which they mean it alternates between paved stretches and unpaved stretches), but did not cause any problem for the car we were driving.