The largest yacht in the world measures an astounding 482 feet (147 m ) long – about half the length of a commercial ocean liner ! it features 60 guest rooms , two swimming pools , and a helicopter pad .It was built in the vospers ship yard in England in 1984 . This royal yacht was named after its qwner , prince Abdul Aziz of Saudi Arabia . When he acquired the yacht in 1987 , it was estimated to be worth more than $ 100 million in U.S. currency . At the time , the prince was just 18 years old , but was already worth about $1 billion .