Here is the patrol submarine K I of the Royal Netherlands Navy. Active from 1914 to 1928, the Ministry of Colonies ordered this slender submarine for service in the Dutch East Indies. In order to operate in the hot climate of the Pacific Ocean, this craft had a large cooling system, which a crewmember eventually fed into the ventilation system, giving this submarine an air conditioning system prior to its official invention.

This submarine, which was built by me, was photographed by xYoshii_. Enjoy!