Lonar Crater Lake

50,000 years ago, a meteorite struck what is now Buldhana district of Maharashtra, creating a crater 1.8km in diameter and 150m deep. The resulting lake is scientifically unique in two ways: it is the world's only hypervelocity impact crater in basaltic rock (all others are in granite), and the lake contains both saltwater and freshwater zones with a sharp boundary, supporting entirely separate ecosystems on each side.

The lake changes colour seasonally — green, pink, and red at different times of year, depending on the algae populations. Around its rim, 13 temples dating from the 12th to 13th centuries are partly submerged, partly standing — Daitya Sudan Temple, Kamalja Devi Temple, and others that archaeologists are still studying.

Lonar is 5 hours from Aurangabad (near Ajanta and Ellora) and 7 hours from Nagpur. It receives fewer than 15,000 visitors per year despite being a Geological Survey of India national monument, a Ramsar-listed wetland, and scientifically analogous to craters on Mars. It is absurdly unknown.