Flying Dutchman

The Flying Dutchman is a mini-boss that spawns during the Pirate Invasion event. It has four cannons that drop cannonballs, and it will occasionally spawn standard Pirate Invasion enemies. The Flying Dutchman does not disappear after the Pirate Invasion is over (though it will explode if it has not been engaged before the invasion ends), and defeating the Flying Dutchman will not end the invasion. The Flying Dutchman can only be defeated by destroying all four cannons. Several Flying Dutchmen can appear during a single Pirate Invasion, or none at all. They seem to only appear once the event progress has passed 50%.

Tips

 * They can be easily killed with a minecart and a sufficiently long track, with the cannonballs only hitting the player if they slow or stop. This makes them fairly easy if you have a decent ranged weapon.
 * Due to the way it moves, and the way the cannonballs fire, it is very easy to find positions where it cannot hit you, yet you can hit it.
 * Due to the fact that they stop upon hitting a wall, and continuously spawn enemies pertaining to the pirate invasion, the Flying Dutchmen can be stopped above a half block deep pit of lava (or other trap) and used to farm the various items pertaining to the pirate invasion.

Trivia

 * In real life, during the 17th century, the Flying Dutchman was a mythical ghost ship that would float above the ocean. Seeing the Flying Dutchman was regarded as an omen of doom.
 * The flying dutchman is the only mob in the game to have special gibs. When the flying dutchman dies, the sail rips to shreds and gently floats down.

History
Hollandais Volant