Concept:Identifying major seaports of India and recognising a location that is not a seaport.
Explanation:Paradip, Jawaharlal Nehru Port, and Dhamra are all established seaports in India.
Paradip is a natural port in Odisha that handles iron and aluminium exports.
Jawaharlal Nehru Port (JNPT), near Mumbai, is a major container port.
Dhamra is a deep‑water port also located in Odisha.
Diamond Harbour is a town on the eastern bank of the Hooghly River in West Bengal.
It is not a functioning seaport; the nearest major port is Haldia, which is sometimes historically referred to as Diamond Harbour.
Therefore, Diamond Harbour is the only option that is not a seaport.
Answer:Diamond Harbour