Authorities check the turtles' health.
The four turtles weighing 56 kilos in total were earlier kept as pets at a local tourist site. They were in stable health condition.
The owner said that he bought the animals a year ago from some fishermen who caught them at sea.
According to the authorities, the four turtles belong to rare, endangered species that need urgent protection. Activities including trading, keeping, and slaughtering are banned.
The animals were released back into the sea in the Ke Ga area on December 18.
Sea turtles are usually found in warm waters in the Pacific Ocean and Indian Ocean. However, their numbers have sharply decreased due to illegal hunting and trading. In Vietnam, sea turtles are listed in the Red Book.
In Binh Thuan's islands of Phu Quy and Hon Cau, there have been many activities held to raise public awareness on the protection of sea turtles. Turtle eggs are carefully protected by volunteers to ensure baby sea turtles hatch from their nests and go back to the sea safely.