Maharashtra: Lonar Lake

Lonar Lake, in Buldhana district, is India's most exam-favoured single lake fact: it is the country's only confirmed meteorite-impact crater lake, formed when a meteorite struck the Deccan basalt plain an estimated 35,000 to 50,000 years ago (differing scientific estimates place it across this range; treat both figures as acceptable approximate answers). The impact crater is roughly 1.8 km in diameter and about 137 m deep, and the lake within it is both saline and alkaline — an unusual combination that supports a distinctive microbial ecosystem found in few other places on Earth. Lonar Lake occasionally makes current-affairs headlines when its water turns a sudden pink or reddish colour, an effect attributed to salt-loving (halophilic) algae and bacteria blooming under specific temperature and salinity conditions — most famously documented in June 2020. Its basalt setting is itself notable: Lonar is one of only a handful of impact craters in the world formed in basaltic rock rather than more common target rocks, giving it scientific importance beyond India (NASA and other international researchers have studied it as an analogue for craters on the Moon and Mars).

Memory hook: "Lonar: India's only meteor-crater lake, saline-alkaline, and it occasionally turns pink." Three facts glued to the one detail (meteor) that makes this lake unmistakable.

Practice Recall: Before reading on, name India's only confirmed meteorite-impact crater lake, the state it is in, and roughly how old the impact is estimated to be.

Answer: Lonar Lake, Maharashtra; roughly 35,000–50,000 years old.