Lake Tuzla, also known as "Balchik Salt Lake", is a coastal lake located in the northern part of the Bulgarian Black Sea coast, about 5 km east of Balchik, and is characterized by its extremely salty water, with salinity ranging from 28% in the east to 160% in the west, which makes the salt concentration in it close to the water of the Dead Sea. The mud of this lake has great healing properties, because it has excellent physical and chemical properties, and it has been used since the early eighteenth century.