If you watch carefully, you will discover a lot of ruins right along the beach side. There are walls lining up above, probably remains of a fortress, ruins of a castle on the right side up the hill and I think a small church also on the right side of the beach.
The beach in Olympos is beautiful, backed by ancient ruins and stunning rock formations in the cliffs, and fronted by blue seas with boats bobbing up and down.
It is really pretty, dont go expecting sand though. The beach is made up of pebbles, so it can be a little hard on your feet! The water though is clean and perfect for swimming in.