Étang de Bolmon, body of water in Provence-Alpes-Côte d'Azur, France

Étang de Bolmon is a shallow coastal lagoon near Marignane, with calm blue-green water and dense reed beds along its edges. A raised wooden boardwalk crosses part of the wetland, leading to three bird observatories where visitors can watch ducks, coots, and herons without stepping onto fragile ground.

Étang de Bolmon is a brackish lagoon separated from the Étang de Berre by the cordon du Jaï, a strip of land 6 km long and 100 to 300 m wide. In 1991 the neighbouring communes of Marignane and Châteauneuf-les-Martigues created the Syndicat Intercommunal du Bolmon-Jaï (SIBOJAÏ) to manage the site. In 2026 the Gipreb began reopening the three bourdigues linking the lagoon to the Étang de Berre, with two hydraulic windows on the canal du Rove.

The lagoon's Provençal name for coots, macreuses, recalls the battues once held here: up to 10,000 birds were counted, encircled by rowing boats despite the vast seagrass beds. Around 25 night-hunting huts still stand on the Marignane and Châteauneuf shores. A discovery trail with bird observatories runs around the lagoon.

The walking route is flat and easy to follow, with a boardwalk suited to strollers and wheelchairs. The trail begins just past the Jaï district, so come in the morning or late afternoon when bird activity is higher and the low sun makes the water easier to watch.

A few abandoned boats lie half-sunk near the shore, their hulls now used by grey herons as quiet perches. In spring, wild orchids appear in the damp ground close to the trail, an easy detail to miss when the water attracts all the attention.