The Nimitz class aircraft carriers currently in service for the US Navy weigh anywhere from 102,000 to 106,000 metric tons.
If these gigantic ships weigh so much, why don't they sink?
The way a ship floats is not only dependent on its weight. Even though the ship is extemely heavy, it displaces an amount of water which weighs the same amount as the ship. If more of the ship goes under, the weight of the water it would displace would be more than its own weight. This phenomenon causes the water to exert a buoyant force, counteracting the weight of the ship and allowing it to float.