Sault Falls (also known as Errard Falls as well as Dennery Falls) we think is perhaps St Lucia's most scenic waterfall falling some 15-20m over a rounded cliff. It's one of the few accessible waterfalls on the eastern side of the island near the fishing town of Dennery (though I heard it belongs on the Errard Plantation). It was quite a quiet and relaxing spot and certainly worth the effort to get to as far as we were concerned.
Once we were able to park the car (see directions below), we followed a trail as it descended towards the Dennery River. We got blocked views of the falls from here, but we were able to proceed by getting a little wet crossing the river to get right up to the falls. Having been to tropical destinations before, we knew to bring water shoes (like Keens).
There were a couple of folks who were on their out when we showed up. So that left Julie and I to have the falls all to ourselves. When we left, there was another couple that were about to have the falls to themselves. Indeed, this was one of the quieter and more pleasant waterfalling experiences that we could recall on the island of St Lucia, and we were very glad to have found this spot.
Directions: In order to get to Sault Falls, we rented a car in Gros Islet in the north of St Lucia and self drove to Dennery on the east side of the island.
Once in Dennery, we had to look for a road that led inland nearby the Dennery River. Once found, we continued along that road, which was a mostly smooth paved road. Eventually, we reached some zipline tour area (I believe they were called Treetop Adventures). Then, we continued for a couple of minutes more, veering left at a fork, until we saw a shack with garbage bags around it. That shack was the trailhead.
Next, we had to find parking in one of the pullouts, where there wasn't much room, and we made sure not to block the entrance.
Since we don't have an atlas or decent map showing road names and numbers, we necessarily had to be vague about the directions here. Plus, the waterfall was not that well signposted. We even asked a very helpful guide at the Treetop Adventures area to verbally tell us where the falls were (which happened to be very close to their ziplining facility).