The bottom of the Baie de Saint Brieuc is divided into 2 handles (the cove of Morieux and the cove of Yffiniac), separated by the peninsula of Hillion (cf round zoom on previous map and map below ).

This bay bottom is a territory rich in industrial and economic past, endowed with an exceptional natural heritage and equipped with two cultural facilities: La Briqueterie (Langueux) and Maison de la Baie (Hillion).

The Reserve extends on the bottom of bay as described previously, namely on Anse d'Yffiniac and Anse de Morieux. Located in the heart of the Nature Reserve, in an enchanting setting, the Maison de la Baie is a museographic equipment whose primary vocation is to make the bay discover all the public in order to better protect it.