The Atlantic coast south of Rabat has a string of beaches, most reachable by taxi or bus within 30 minutes. The city beach at Rabat itself is crowded in summer; the beaches further south are better.
Temara Beach (15 km south) is the most popular family beach — wide, sandy, and relatively calm. The small resort town of Temara has hotels and restaurants.
Plage des Nations (Sidi Bouknadel, 15 km north) is quieter, named for the diplomats who used to swim here. Be aware that the currents outside the central lifeguarded strip are dangerous — the Atlantic here is not the Mediterranean.
Mehdia Beach (30 km north) attracts surfers. The old Portuguese fort, the Borj el Kebir, overlooks the beach from the cliff above the Sebou river mouth. Less commercial than Temara.