A blissful site is Bassin La Paix, in the Rivière des Roches valley, about 2.5km west from Bras-Panon (it's signposted). From the car park, a path quickly leads down to a majestic waterfall tumbling into a large rock pool. It's an ideal picnic spot. For a more off-the-beaten-track experience, you can continue upstream to Bassin La Mer, another cascading delight that can be reached on foot only. The start of the trail is at the end of the car park.
It's an enjoyable (though exposed and hot) 40-minute walk. Reward yourself with a dip in the swimming holes at the bottom of the falls.