The Ram Setu (or Adam's Bridge, as it is also known) is an enormous chain of limestone shoals stretching 48 km between India and Sri Lanka that connects through Mannar Bay to Palk Strait.
Hindu mythology claims that Lord Rama and his Vanara (monkey) army used this bridge to cross over into Lanka in order to rescue Goddess Sita from demon king Ravana. According to Hindu epic, this bridge was built within one night by Vanara troops, and existed completely above sea level until 1480 when natural disasters caused its submergence.