As per Hindu Puranas, Bhuloka or earth divided into sapta dwipa or seven continents and the gap between these seven continents was filled by the Sapta Sagara or Seven seas. The details regarding the Sapta Sagara are found in the Skanda Purana and Bhagavad Purana. The liquid content of the seven seas are different. The seven seas are made of saline water, milk, wine, curd, ghee, sugarcane and sweet water.
The first island Jambudwipa is surrounded by saline water.
The second island is the Sakadwipa and is surrounded by Kshirasagara, the sea of milk.
The third island is the Pushkaradwipa and is surrounded by Surasagara, the sea of wine.
The fourth island is Kushadwipa surrounded by dahisagara, sea of curd
The fifth island is Kraunchadwipa surrounded by Ghrtasagara, sea of ghee
The sixth island is Salmadwipa surrounded by Ikshurasagara, sea of sugarcane juice.
The seventh island is Gomedadwipa and is surrounded by sweet water.