Answer: 21 June
Notes: World Hydrography Day, observed on June 21, is led by the International Hydrographic Organisation (IHO) since 1921. The IHO coordinates global efforts to survey and chart seas, oceans, and navigable waters. With 100 member states, it promotes uniformity in nautical charts and best practices. India, a member since 1955, operates the Indian Naval Hydrographic Department in Kolkata, central to hydrographic surveys with a modern fleet. The 2024 theme focuses on enhancing marine safety, efficiency, and sustainability.
