勒拿湖（Lake Lerna），是曾经存在于希腊伯罗奔尼撒半岛南部的一个湖区，由许多喷泉、湖泊和沼泽组成，该地以九头蛇的故乡闻名。

根据地质学家的勘探，发现勒拿湖是一个位于阿尔戈斯以南爱琴海边的一个淡水潟湖，早在新石器时代湖岸便已有人类活动的遗址，但是由于未知的原因遭到了废弃。到了青铜时代，该湖虽然已经遭到一定的瘀塞，直径仍有约4.7公里。迈锡尼兴起之后，该湖沿岸变成了墓地，在公元前12世纪中叶，该湖再一次被废弃。随着周边森林被破坏殆尽，勒拿湖逐渐缩小，变成了一片沼泽，最后的遗存也在19世纪彻底消失。

In classical Greece, Lerna (Greek:Λέρνη) was a region of springs and a former lake near the east coast of the Peloponnesus, south of Argos. Its site near the village Mili at the Argolic Gulf is most famous as the lair of the Lernaean Hydra, the chthonic many-headed water snake, a creature of great antiquity when Heracles killed it, as the second of his labors. The strong Karstic springs remained; the lake, diminished to a silt lagoon by the 19th century, has vanished.