Palmarin's Atlantic side is a long, quiet beach rather than a developed resort front. It is good for walking, watching fishing boats, and letting the wind and surf set the pace of the day.
The beach alone would not justify the trip, but it gives Palmarin its balance: mangroves and salt to the east, open ocean to the west, and Sereer villages in between. Conditions can change with currents and weather, so ask locally before swimming.