Isonzo Mouth Regional Natural Reserve, Regional nature reserve at the Isonzo river mouth, Province of Gorizia, Italy

The Isonzo Mouth Regional Natural Reserve is a protected area at the point where the Isonzo River meets the Adriatic Sea, straddling the provinces of Udine and Gorizia. It covers wetlands, brackish lagoons, reed beds, and riverbanks that form a range of distinct habitats close to the coast.

The wetland at the Isonzo mouth was drained in 1937-38, when a dam was built in the delta to link Isola della Cona to the mainland and drainage channels were dug to make the land cultivable. Restoration began only in 1983, when a regional law started reflooding the marshes, and the regional reserve was instituted in 1996. In 2016 it was declared a wetland of international importance under the Ramsar Convention.

The reserve is a well-known meeting point for birdwatchers, who set up along the banks and lagoons to watch species passing through. The landscape shifts with the tides, so the experience feels different depending on when you arrive.

The area has observation posts and offers guided canoe tours with naturalists, which give a different view of the wetlands from the water. Spring and autumn are the best seasons to visit, as that is when most bird species are passing through.

The reserve's Isola della Cona has been monitored for years, and 322 bird species have been recorded there, whether resident, wintering or passing through. The island was once separated from the mainland by the Quarantia canal before a 1937-38 dam linked it by land.