Parc du Marquenterre, Bird sanctuary in Saint-Quentin-en-Tourmont, France.

Parc du Marquenterre covers 250 hectares within the 3,000-hectare Réserve naturelle nationale de la baie de Somme, in Saint-Quentin-en-Tourmont. A small pine wood surrounds the entrance; below a lookout, shallow ponds, reed beds and salt meadows stretch across the estuary, with brackish pools of 8–25 g salt per litre and freshwater channels lined with poplars and willows.

The area became a protected zone for bird observation in 1973. It developed afterward into a major European site for ornithologists and remains an important resting point for migrating bird populations.

This is a place where bird watchers and nature enthusiasts gather to watch species that pass through seasonally. Walking through the park gives you a sense of how birds rely on these different habitats to rest and feed during their journeys.

The park has marked trails that pass through different landscapes and reach observation points where birds can be seen clearly. Sturdy footwear is recommended since the ground conditions vary depending on the season.

The park's name is a compressed corruption of "la mer qui rentre dans la terre" (the sea returning into the land), describing how the tide pushes salt water upstream beneath the Somme's fresh water. All three trails end at a breeding enclosure for the little egret, the only one of its kind in France.