Seagate Amusement Park

The Seagate Amusement Park was an off-shore oil rig that was turned into an amusement park that served as one of the Joker's bases of operations. It was new in the Arkhamverse, and first appeared in Batman: Arkham Knight, but only in the background. It officially appeared in Batgirl: A Matter of Family.

Before A Matter of Family
Under the advice of his close friend, Doctor Harleen Quinzel, oil baron Edward Burke constructed the Seagate Amusement Park for his ill-stricken five year old daughter, Katie Burke. After showing Dr. Quinzel drawings made by Katie of the amusement park, Edward was introduced to a close associate of hers, Jack White (an alias of The Joker), who assisted in the creation of the park. During the construction of the park, Jack referred Katie to Penelope Young, who treated her with Titan. He also "convinced" some inspectors to open the park, despite there being numerous safety violations.

Once the park was completed, Jack had Katie killed with an overdose of Titan, leaving Edward distraught. Since he no longer had anything left to live for, Edward committed suicide with pills given to him by Jack. Little did he know that the pills were laced with Smilex, resulting in him laughing to death. Once Edward died presumably on July 4th, the Joker and Harley Quinn took over the amusement park officially.

A Matter of Family Incident
Three years before the events of Batman: Arkham Asylum, ​the Joker and Harley Quinn, along with a large following of their henchmen, abducted Commissioner Gordon, and announcing that if Batman attempted to intervene, they would kill him instantly. Believing it her personal duty to ensure her father's freedom (as well as to prevent Batman from having to go), Batgirl, assisted by the new Robin, Tim Drake, made her way to Seagate on a rescue mission.

Unbeknownst to them, that had been Joker's plan all along. Insisting that their allegiance to Batman interfered with Joker's and Batman's "crazy little game", it was his intention to eliminate the duo and presumably the commissioner too.

Eventually, the Joker's plan was foiled when Batgirl and Robin dispatched the majority of Joker's Henchmen and engaged the Clown Prince of Crime, Harley, and their remaining forces in a hand-to-hand brawl. Soon afterwards, the GCPD were called in for backup, though were they unable to detain Joker before he made a leap from the edge of the Seagate platform and was carried away by a parachute.

That was one of the last major acts in Batgirl's career before she was paralyzed by the Joker.

Arkham Knight Incident
During the events of Arkham Knight, Seagate Amusement Park could be seen best from Miagani Island, and sat on the coast of a peninsula in the Gotham City Bay. In a state of complete disrepair after its abandonment by the Joker's Henchmen, it was empty, like much of the quiet outskirts nearby.

Layouts
A reconstructed oil rig off the shore of Gotham City made into an amusement park, this giant establishment was not a small feat for just anybody. Fortunately, Edward Burke and his company, Burke & Hox Inc., was affluent enough to afforded a total of $1,804,724. from various business entities, such as the Metropolis Vintage Emporium, Star City Amusement Ltd., Hunza Swiss Ski Resorts, and Coast City Recycling Department for used parts needed to construct the park. The park itself was situated on top of the oil rig, and the guests would enter the park by riding on a gondola cable from the shore.

The park had four main attractions, worthy of being "The Greatest Park in Gotham City." "The Big Blue Ferris Wheel" was strapped with a rocket engine, ensuring the fastest rotating speed never before seen. "The Merry Go Round" was a colossus carousel, with its base submerged in an enclosed water tank. "The Ghost Ship" featured a giant Kraken animatronic at the climax of this horror-themed tunnel ride. Lastly, "The Great White Rollercoaster" boasted a staggeringly high ride from the top of the gas flare, circling down to the bottom.

#1.
"You should know that all this you see around comes from our talks in the hospital. Daddy was paying attention and he used your drawings for inspiration. When I showed them to my friend Dr. Quinzel, she said you were very talented little girl and that I was a very lucky father. Don't I know it!"

#2.
"You may not understand this... but what happened to us... what happened to you... changed my life for the better. Even Dr. Quinzel says I'm much more alive and present since I gave up work to take care of you. Actually... come to think of it... she was the one who suggested I build this place for us. To inspire me, she introduced me to a strange man in a purple suit who gave me a lot of unique ideas for the park. He calls himself Jack White. He's got a great laugh and sense of humor. I think you'd really like him."

#3.
"The scariest day was when the doctors told me there was nothing more they could do for you and that you were going to die. We can be grateful to Jack for referring us to Dr. Penelope Young who did for you what traditional medicine couldn't. It's because of her special treatment that you are here today. I thanked Jack endlessly for referring us and even offered him a new wardrobe... but he told me he was quite satisfied with his wardrobe and didn't seem to pleased about the suggestion. I really hope I didn't offend him after all he's done for us."

#4.
"You know it wasn't easy getting this place up and running. Some inspectors nearly shut us down but Jack somehow convinced them to change their minds. As a thank you gesture I bought him a new purple suit imported from Italy, but he said it was violet and that he only wore purple on account that purple keeps him grounded. I guess your daddy doesn't know the difference between purple and violet. In any case, I have to get Jack something meaningful to thank him for all his help throughout this ordeal."

#5. All other four recordings must be obtained before unlocking the door to this recording
"Katie died before she could see the park. Jack blamed me and said I should have never taken her to Gotham General in the first place... but how was I to know... he told Dr. Young to triple the amount of her alternative meds but that only seemed to make things worse. She died last week and the pain is unbearable... Dr. Quinzel says it won't get better... she says the pain will just get worse and there is no point in going on... she's right... she always is... I signed the park over to Jack and my only hope is that he does something inspiring with it. As for me... I'll be with Katie soon... these pills Jack gave me will make sure of that. Supposed to be painless."