National Nature Reserve of the Bay of Somme, National nature reserve in Saint-Quentin-en-Tourmont, France.

The National Nature Reserve of the Bay of Somme covers 3,421 hectares of tidal mudflats and salt meadows between the Pointe du Hourdel and the mouth of the Maye, on the territory of Saint-Quentin-en-Tourmont. Its land section is the Marquenterre park, with marked trails and observation posts. From above, the sand banks form grey and brown plates cut by silvery channels where small figures stand at the water's edge.

The reserve grew out of a national hunting reserve created in 1968 in the Bay of Somme. Its founding project was drawn up by Jérôme Laurent, Didier Pamelle and the ornithologist François Sueur, and the national nature reserve was formally created by decree on 21 March 1994, covering 3,421 hectares. Since 2012 it has belonged to the Picardy estuaries and Opal Sea marine nature park.

The reserve grew out of a hunting reserve created in 1968; its conversion to a national nature reserve was prepared by Jérôme Laurent, Didier Pamelle and ornithologist François Sueur. Each April the Festival de l'oiseau et de la nature is held here, and the Marquenterre park's marked trails and observation posts let visitors watch birds without disturbing them.

Multiple observation points equipped with binoculars and telescopes allow you to watch seals resting on sandbanks and hundreds of bird species throughout the year. The best viewing conditions occur at low tide when wildlife is most active and visible.

The reserve holds France's largest colony of harbour seals (Phoca vitulina), the country's main site for their breeding and hauling out. The animals rest on the sandbanks at low tide and swim in the channels at high tide. The colony is the reason the bay is also a Ramsar site, listed since 30 January 1998.