The lagoon, which is situated at the foot of Quan Cau Pass near National Highway 1A in Tuy An District, is the shape of a swan when viewed from a plane passing overhead. The 1,200ha wide lagoon with an average depth of 1.2m to 1.4m is surrounded by rolling hills, and linked to the Cai River. A small creek also links the lagoon and the sea.
Golden sand dunes and casuarina forests also line the banks of the lagoon, providing shelter for pelicans, storks and ducks.
One of the most enjoyable things to do at O Loan is to jump into a boat to cruise the lagoon. Local boatmen will take you out across the calm waters, and you may even be surprised to see fish jumping out of the water.
O Loan lagoon is also famous for culinary specialties such as red oysters, cuttle-fish, jelly fish and a type of red algae that is used in food.