Step 1: Locate Kuttanad.
Kuttanad is a unique lowland region in the Alappuzha district of Kerala, often called the Rice Bowl of Kerala due to its extensive and productive agricultural activity.
Step 2: Identify its defining feature.
Kuttanad is one of the very few places in the world where farming is carried out below sea level. It is especially famous for its below sea-level paddy cultivation, a remarkable feat of traditional agriculture sustained through an intricate network of canals and bunds.
Step 3: Eliminate wrong options.
Kuttanad is not associated with rubber, tea, or coffee plantations. Paddy cultivation below sea level is its defining identity.
\[ \boxed{\text{below sea-level paddy cultivation}} \]