Take a walk to a very picturesque beach and a landmark rock.
There is a beautiful walk out to the rock formation and the Virgin Mary statue. When you walk out to the rock formation, you get a great view of the downtown area of Biarritz and the more rural southern end of the town. If you go in the winter time, you can see large waves crash against the rock.
WARNING: Time the walk out accordingly or you will get splashed when the waves are big.