About NHO

National Hydrographic Office, located at Dehradun is the main office of the Indian Naval Hydrographic Department (INHD) and is responsible for all matters of hydrography as applicable to the Indian Navy. The department has a fleet of seven oceangoing vessels well equipped with modern equipment to collect hydrographic details. The office produces standard navigational charts and nautical publications as per the standards and conventions of the International Maritime Organisation (IMO) and the International Hydrographic Organisation (IHO). NHO also produces digital charts in the form of Electronic Navigation Charts (ENC) for use in the Electronic Navigation Chart Display and Information System (ECDIS). The office is also responsible for provisioning of Hydrographic and Marine Safety Services within Indian waters/area of responsibility.

Operation Trident

Operation Trident, a major offensive naval operation during the Indo-Pakistani War of 1971, marked a pivotal moment in Indian military history. Launched on the night of December 4-5, 1971, this operation was spearheaded by the Indian Navy against Pakistan’s Karachi port, the hub of its naval operations. The operation was meticulously planned to strike at night, utilising small yet powerful missile boats, which were well-suited for surprise attacks.

A task force comprising Vidyut-class missile boats, escorted by destroyers and frigates, launched from the Indian coast. They managed to infiltrate Pakistani defences and delivered devastating blows using Soviet-supplied Styx missiles. The missile strikes set Karachi's oil storage tanks ablaze and severely damaged naval assets, including the sinking of PNS Khaibar, a destroyer, and PNS Muhafiz, a minesweeper.

The Indian Navy successfully retreated without suffering any casualties, making Operation Trident one of the most successful naval operations post-World War II.

This attack had a profound impact on the Pakistan Navy, forcing it to retreat to port and remain inactive for the remainder of the war. It also significantly hindered Pakistan’s operational capabilities, disrupting its supply routes and causing widespread damage to Karachi's harbour facilities.

Operation Trident is celebrated annually as Navy Day in India on December 4 to honour the Indian Navy’s achievements and the success of this operation. The operation also showcased India’s growing naval prowess and emphasized the importance of missile warfare in naval battles.

The success of this operation, followed by Operation Python a few days later, played a key role in India’s victory in the 1971 war and established the Indian Navy as a formidable force in the Indian Ocean.