The lagoon behind Grado runs for some 30 km along the coast — a protected area of salt marshes, tidal channels, low sandy islands, and shifting sandbars, much of it within the Riserva Naturale della Valle Cavanata and the Foci dell'Isonzo nature reserves. Greater flamingos, herons, egrets, and large numbers of migrating waterbirds use it, and bird-watching is excellent throughout the year.
Boat trips run from Grado harbour in the season, typically visiting Barbana island, the bird-rich Mota Safon casoni, and the abandoned fishing islets. A more energetic option is to rent a kayak or paddleboard and explore the inner channels yourself — the water is shallow, the currents gentle, and the silence remarkable once you are away from the main town.