Lake Massaciuccoli (Lago di Massaciuccoli in Italian) is a lake in the Province of Lucca. Its surface area is 6.9 km². It is located mainly in the municipality of Massarosa and partly in Torre del Lago, a civil parish of Viareggio. The lake is home to the large extent of Cladium mariscus in Italy. However, vegetation and wildlife have shrunken substantially since the 20th century, due to eutrophication and expansion of Louisianan Crayfish, which are now disappearing from the lake because of predatory birds.