The mud of the lagoon of Messolonghi is famous for its curative action. It is a black-coloured clay with a number of nutrients, minerals and trace elements, such as calcium carbonate, organic substances, etc., which comes from the dissolution of rocks into very fine particles. Its dark colour is due to the sulphur salts it contains, which are an important therapeutic ingredient. When the clay comes into contact with the skin, a chemical reaction takes place in which the acidic components present in our skin react on contact with the mud and give us sulphur ions, which are absorbed by the skin, relieving various dermatological conditions. The mud baths in the area of the lagoon of Messolonghi have been famous for hundreds of years for their beneficial effect on a number of skin diseases and more. Modern studies have proven their positive effect against osteoarthritis.