The pirate ship, known as the Hei Zhenzhu, can sail between a few locations like Shoreline, Kakuri Island and Botany Bay. It doesn't dock with land ports (that's a landlubber's job, see) so you'll have to either swim out to where it sits close to shore and , or else a boat from the nearby port and then with the ship to reach it.
There's a bunch of pirates and rats to greet you once you're on board, some of which may attack you at will. Both of these mobs will most likely only give trouble to low to mid level characters. There's also some sort of cannon on the aft deck which might be worth experimenting with, and a strange smell-based mystery... A couple named mobs hang out here too. Lai Ping is the area's miniboss, she's aggressive and uses a rusty AK-7. She's not notable in any other way. There's also Captain Wei, who uses (and drops) a regular AK-7 but isn't aggressive. He's supposed to be part of a quest in Botany Bay, but everybody just skips him because his portion of the quest is optional and takes forever. He does drop a trophy if you beat him up though! Finally, Raider Bosses tend to end up here from time to time. You'll have to track them down aboard the ship on your own.
The pirate ship is also notable for being one of HellMOO's buggiest zones. it is possible to lock yourself in the brig on accident, and the ship has very poor pathing; it often gets stuck in the middle of nowhere, or else seems to disappear from the world altogether.