Which one of the following is not a sea port?

Diamond Harbour is not a sea port; it is primarily a river port and pilot station located on the eastern banks of the Hooghly River in West Bengal. While it serves as a major tidal port and a point of navigation for vessels heading toward Kolkata, it is situated inland rather than on the open sea [2]. In contrast, Paradeep is a natural, deep-water sea port in Odisha located at the confluence of the Mahanadi River and the Bay of Bengal. Haldia is a major seaport developed downstream from Kolkata to accommodate larger modern ships and relieve congestion [1]. Dhamra is also a significant deep-water port on the coast of Odisha. Therefore, Diamond Harbour is distinguished by its riverine and tidal nature rather than being a coastal sea port.

Sources

1. [2] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 32: Ocean Movements Ocean Currents And Tides > Explanation: > p. 508
2. [1] Geography of India ,Majid Husain, (McGrawHill 9th ed.) > Chapter 12: Transport, Communications and Trade > Ports > p. 20