Nessebar is a popular visitor destination for its historic Old Town and lovely beaches on the Black Sea. They are lovely beaches but are often not great for running, as the sand tends to be soft, except right near the water.

Sunny Beach Promenade. Google Street View

There are two main beaches in Nessebar. South Beach, which is adjacent to Old Nessebar, is 1 km long. It’s a festive scene, and can be crowded. 

Just north of Old Nessebar, there’s a 5 km long beach that includes Baby Beach, Cacao Beach, and Sunny Beach. Sunny Beach is the most developed, and is lined with apartment buildings, shops, and restaurants. There’s a 2.8 km paved promenade that runs along Sunny Beach, which features some nice beach & water views, though there are also buildings blocking the view for much of the way. The sand on Sunny Beach is soft for running, but you might have some luck right near the water.