A secret super yacht dubbed “Project Azzam” costing $627.4 million is being built for Sheikh Khalifa bin Zayed Al Nahyan, president of the United Arab Emirates, Page Six has exclusively learned. At an estimated 590 feet, it could surpass the length of some cruise ships and is primed to be an object of great envy on the Riviera’s rich-boys-and-their-toys scene next year. Photographers caught sight of a portion of it last month when it outgrew one dry dock at fancy German shipbuilder Lürssen, fueling wild speculation over who its owner could be. Previous talk was that the colossal craft was for Saudi royal Al-Waleed bin Talal. But sources tell us it’s for Sheikh Khalifa. It will even eclipse Russian Roman Abramovich’s $485 million Eclipse at 536 feet. Unlike most propeller yachts, Azzam is said to boast a custom propulsion system with four giant water jets, to make it one of the fastest on the seas. Reports say the gas guzzler’s tank would have to hold an astounding 264,172 gallons of fuel. Only two locations reportedly could accommodate a yacht so big — Monaco and Antibes, although sources said Sheikh Khalifa wants to cruise the Seychelles. A rep at the UAE Embassy in Washington, DC, declined to comment. Also on the yacht scene, we exclusively reported that Microsoft mogul Paul Allen is lending his yacht, Octopus, to help recover a prized artifact from a sunken, British World War II battle cruiser HMS Hood. The boat will embark on the mission with the British Royal Navy after the Olympics wraps.