Visiting the waterfalls is the most popular day trip from the mountain city; almost tourist you talk to has already gone or is making plans to head that way. To get there, hop in a grand taxi, which can be found in the circled area on the map:
We paid 300 dirham total for five people. Our driver drove us there, waited on us while we hiked, and then drove us back. Thankfully he waited on us as we were almost three hours after our agreed meeting time and had no cell phone service to call and let him know! (Side note: always tip drivers in Morocco for longer drives).
The drive itself is about 45-minutes, through the mountain ranges, so there are some gorgeous views. If you get hungry, stop along the side of the road on the way and try some berries or cactus fruit! Once you get there, there are two waterfall routes to pick -- and everyone will give you different information on how far away it is. We opted for the "small waterfall" route and were very happy with it. Once you walk through the sales area, turn left to go over the bridge. The water will then be on your right, follow that trail for about an hour until you get to the small waterfall. There is a sign that says "small waterfall ici" and there are usually a lot of people, so it's somewhat hard to miss (although definitely very, very possible). There is a larger waterfall about an 1.5 hours further, but when we went it was far too dry in the middle of the summer and not at all worth it.
If you stay at the small waterfall, you can order a tagine and while waiting for it to cook you can swim, cliff jump, and enjoy the amazing view!