St. Anastasia is an island in the Bourgas bay in the Black Sea. Between 1945 and 1990 the island was named Bolshevik.  It is located 6.5 km southeastern from Burgas, between St. Anastasia cape and Atia cape.

The island is formed of volcanic rocks, it is 12 m high and its area is 0.022 sq.m. In 1924 the island was turned into a concentration camp. An old dried up well is situated in the northern part of the island.

The legend tells that many centuries ago a pirate treasure was hidden here. From time immemorial the island is known as a hiding place of the pirates, raving once in the Black Sea. A lot of treasure hunters have tried their chance here, but no one has ever found the treasure. Apart of it, the legend attracts each year many tourists from entire Bulgaria.

Today the island is owned by the Bulgarian Orthodox Church, but a local businessman manages it from a few years.