Vembanad Lake, Kerala's largest lake and generally cited as India's longest lake, stretches roughly 96 km along the coast through Alappuzha, Kottayam, and Ernakulam districts, forming the core of Kerala's famous backwaters — the network of interconnected lagoons, canals, and estuaries used for houseboat tourism and traditional rice cultivation on reclaimed, below-sea-level paddy land (the Kuttanad region, sometimes called "the rice bowl of Kerala," sits partly below sea level along Vembanad's shores, an unusual agricultural-geography fact worth remembering alongside the lake itself). It is a lagoon formed where several rivers (including the Pamba, Meenachil, and Achankovil) meet the Arabian Sea behind a barrier of coastal sandbars, and it carries the Ramsar designation as the Vembanad-Kol Wetland.

Ashtamudi Wetland, further south near Kollam, is another significant Kerala backwater lake system and a separate Ramsar site in its own right, distinguished by its unusual eight-armed ("ashta" = eight, "mudi" = knot/branch) shape branching out from a central point — a useful visual detail if a question describes the lake's shape rather than naming it directly.

Memory hook: "Vembanad is longest and holds Kuttanad's below-sea-level rice; Ashtamudi's eight arms branch out further south." Kerala's two headline Ramsar lakes, kept apart by length and shape.

Practice Recall: Before reading on, name India's longest lake, the state it is in, and the low-lying rice-growing region on its shores.

Answer: Vembanad Lake, Kerala; the Kuttanad region.