Platja de la Marineta Cassiana is the easy beach south of Denia's centre, a sheltered strip of sand and calm water at the start of the route toward Les Rotes. It is not wild Costa Blanca, but it is practical, close, and good for a slower swim than the rougher rocky coves farther along.
The promenade is part of the appeal. Use the beach as the beginning or end of a waterfront walk, especially outside the hottest hours, when the view back toward town and the Montgo side of Denia is more enjoyable than simply lying on the sand.