Submarine Day is celebrated by the Indian Navy on the 8th of December. It marks the day on which the Indian Naval Ensign was unfurled on India’s first submarine, INS Kalvari at Riga, Latvia in 1967. The name ‘Kalvari’ is a Malayalam term for ‘Tiger Shark’- a predatory species occurring in the Indian Ocean. It is a diesel-electric submarine from the Foxtrot Class, from the erstwhile USSR. The submarine was decommissioned in 1996.