瓦登海（荷兰语：Waddenzee、弗里西语：Waadsee、低地德语：Wattensee、德语：Wattenmeer、丹麦语：Vadehavet）指的是欧洲大陆西北部到北海之间的一块浅海及湿地。瓦登海北起自丹麦南部的海岸，遂向南至德国海岸后又转向西到荷兰。与北海之间有弗里西亚群岛分开。瓦登海拥有丰富的生物多样性资源。2009年，瓦登海的荷兰和德国部分被联合国教科文组织列入世界遗产。

据C·迈克尔·霍根的研究，瓦登海是全球海洋中海岸线被人类改变最多的海洋之一，这种改变通过陆地和低洼沿海的岛屿上的堤坝和堤道系统。瓦登海从荷兰西南部登海尔德开始延伸，穿过德国的大河河口至其丹麦埃斯比约，全长约500公里，总面积约10000平方公里。

The Wadden Sea (Dutch:Waddenzee, German:Wattenmeer, Low German: Wattensee or Waddenzee, Danish:Vadehavet, West Frisian: Waadsee, North Frisian: di Heef) is an intertidal zone in the southeastern part of the North Sea. It lies between the coast of northwestern continental Europe and the range of Frisian Islands, forming a shallow body of water with tidal flats and wetlands. It is rich in biological diversity. In 2009, the Dutch and German parts of the Wadden Sea were inscribed on UNESCO's World Heritage List and the Danish part was added in June 2014.