The whole area from Balchik to Durankulak is rich in beautiful diving spots. If you have not tried it before, you can take diving lessons or dive below the water with an instructor. If you have experience, then the diving centre will provide you with the necessary equipment and support.
You can explore the underwater caves near Rusalka, the fairy caves and the rocks along Kamen Briag, the inaccessible (when seen from above) shores around Cape Kaliakra. Yaylata and Tyulenovo also have a lot to offer in this aspect.
Diving is an unforgettable experience, do not miss it.