Take the road you would take to get to the Pinel ferry. Before the end of the road, however, take a left turn up the hill. There will be signs to the Riu, and I think there's a school on one of the left corners.

Take the windy ride up, and down, the hill. You will go through a gate (not staffed) that takes your picture. At the bottom of the hill, go toward the staffed guard shack. Just before the shack, take a left into the parking lot. Go through the parking lot to a street that parallels the parking lot. Take a right and follow the signs to Anse Marcel Beach Café/Restaurant. You will not be sorry you made the effort!