Level 79-81 Boss Ship of the Line. It is only encountered so far in Royal Navy Treasure Fleets along with the Navy Elites. It attacks with extremely powerful Explosives for Cannons and Round Shot for Broadsides. They have tremendously thick hull armor. They can engage targets from fairly long range and are surprisingly fast and agile for their size, and can travel with no sails. Currently, these ships have only appeared as part of Treasure Fleets and have no permanent patrol routes. The HMS Invincible, like all other Treasure Fleet ships, can also fire two shots out of a single cannon; added with the fact that she uses powerful Explosive deck guns, this makes her a highly dangerous ship, perhaps even the strongest enemy ship at sea.
- The name of this ship seems to come from its real live counterpart, the Invincible, a massive French Navy Ship Of The Line which was captured by the British Royal Navy in 1747 and renamed HMS Invincible. The HMS Invincible was one of the first 74-gun Ship Of The Line in the Royal Navy. At the First Battle of Cape Finisterre, while still held by the French, she alone attacked 6 British warships to let the convoy she was escorting to escape. HMS Invincible sank after hitting a sandbank in the East Solent. Her wreck is still viewable today.