This 'Fosse de la Vise' is the source of a hot spring that feeds the spa in Balaruc.

Early settlers described this as "une petite mer intérieure et tranquille" ("a small, calm, inland sea").

There are harbours in the towns of Marseillan, Mèze and Bouzigues, with smaller ports dedicated to shellfish on the northern shore.

Located between the towns of Sète and Marseillan in the Hérault département, the Étang de Thau is shared administratively by the communes of (running clockwise), Balaruc-le-Vieux, Balaruc-les-Bains, Frontignan, Sète, Marseillan, Mèze, Loupian and Bouzigues.

[6] Fixed with cement to ropes, the young oysters are immersed in the water until they reach a size suitable for consumption.

Apart from fishing and shellfish, the Étang de Thau provides income through tourism, particularly via sailing schools.

The Bassin de Thau provides a habitat for a variety of wild animals, notably birds such as herons and pink flamingos[5] and a rich marine fauna, including bivalves (oysters and mussels), jellyfish, fish, and algae.