Jeita Grotto, Limestone cave system in Keserwan District, Lebanon.

Jeita Grotto is a limestone cave system in Keserwan District, Lebanon, extending roughly nine kilometers through underground chambers. The complex divides into an upper gallery with walkways and a lower section navigated by boats.

Reverend William Thomson, an American missionary, entered the lower cave about 50 metres in 1836 and fired his gun; the echoes convinced him the cavern was large. In 1873–74 engineers W.J. Maxwell and H.G. Huxley with Reverend Daniel Bliss reached 1,060 metres, stopped by the underground waterfall called Hell's Rapids. The lower cave opened to the public in 1958; the upper galleries, found that year, opened in 1969.

The cave's name changed several times: it was first called Nahr al-Kalb cave, then Djaita and Jehita, before Jeita, a name newspapers adopted widely in 1927. In Aramaic Jeita means "roaring water". In 1961 Lebanon issued a stamp showing the lower cave, and the boatman on it, Maroun al-Hajj, was still rowing visitors four decades later.

Guided tours take visitors first into the upper cave, where you walk through lit passages, and then into the lower level, where small boats glide across the water. A cable car connects the entrance to the upper parking areas, and an electric train shortens the walk between the two cave sections.

The underground river supplies drinking water to more than one million people in the surrounding area and flows year-round through the lower cave. In winter the water level rises so high that boat tours pause, while the upper gallery remains open.