大苦湖（阿拉伯语：البحيرة المرة الكبرى‎；音译︰al-Buhayrah al-Murra al-Kubra）是苏伊士运河北部和南部之间的咸水湖，由小苦湖（阿拉伯语：البحيرة المرة الصغرى‎；音译︰al-Buhayrah al-Murra as-Sughra）连接，大苦湖和小苦湖的总面积约250平方公里。在苏伊士运河落成前，大苦湖的所在地是铺满盐的山谷。由于运河没有水闸，海水可从地中海和红海经曼扎拉湖（Lake Manzala）和Lake Timsah流入大苦湖，鱼类能从红海经运河和湖泊向北迁徙至地中海东部。一般来说，北部的水流方向随季节改变，冬天向北流动，而夏天向南流动；南部的水流与红海的潮汐相反。

The Great Bitter Lake (Arabic:البحيرة المرة الكبرى‎; transliterated: al-Buhayrah al-Murra al-Kubra) is a saltwater lake which is part of the Suez Canal. It is connected to the Small Bitter Lake (Arabic: البحيرة المرة الصغرى; transliterated: al-Buhayrah al-Murra as-Sughra), through which the canal also runs. Before the canal was built, their site was occupied by dry salt valleys. Together, the Bitter Lakes have a surface area of about 250 km². The canal also runs through Lake Manzala and Lake Timsah, north of the Bitter Lakes.