India’s deepest port is:

Paradip is the correct answer. It sits on the Odisha coast near the Mahanadi mouth and has a natural draft of about 14 to 16 metres, which dredging has pushed to roughly 17 to 18 metres. That makes it the deepest major port in India. It is one of the 12 major ports under the Centre, now governed under the Major Port Authorities Act, 2021, which replaced the Major Port Trusts Act, 1963.

• Kandla (Deendayal Port, Gujarat): a tidal port in the Gulf of Kutch. Its channels depend on tides and it needs constant dredging, so its draft is shallower than Paradip. It was renamed Deendayal Port in 2020.
• Cochin (Kochi, Kerala): a natural harbour but with a much shallower draft, and its channels need regular maintenance dredging.
• Marmagoa (Mormugao, Goa): a good natural harbour, but its working draft is well below Paradip's.

Core concept: draft and natural versus dredged depth of major ports. For Mains, port depth links to infrastructure, Sagarmala and the question of evacuating large ships and bulk cargo from eastern ports.

Trap: aspirants pick Kandla or Cochin because they are older or better known. Depth is a separate fact from size, traffic or age of the port.