The footage was caught by a passer-by who initially thought the rider was a nun - which, to be fair, would be a bit cooler.
The onlooker filmed The Joker as he played around on the water, and later uploaded the clip to Twitter.
They said: "At first, my friends and I thought it was pretty weird because he was skiing from quite a distance. We actually thought it was a nun or something because he was wearing a long suit.
"But when he got closer, that's when we realised it was The Joker. We thought it was being filmed, but we eventually concluded it was for leisure."
The fella was there for a few hours, entertaining the crowd that had gathered to watch.
As you can imagine, the subsequent clip of The Joker on a jet ski caused a bit of a stir online.
Responding to the clip, one Twitter user wrote: "Nah this is funny as hell. I don't know WHAT I would do if I saw this in real life. But it IS 2020 and the way this year has gone... are we REALLY surprised??"
A second joked: "Why he dressed like when you're in a Zoom meeting with work (suit on top and shorts/sweats on bottom)."
While a third said: "At this point in 2020 you'd have to convince me that this ain't the real Joker."
Weirdly, this isn't the first time The Joker has been spotted on his water ski in the East River - a quick search on Twitter pulls up sightings from 2018.
In 2019, the actress Olivia Wilde even got a glimpse of the cartoon villain messing about on the water. Posting on Twitter, she wrote: "I s*** you not - I saw The Joker riding a jet ski in the East River today. Purple suit, face paint, the whole lewk. I swear on my life. Someone pls tell me you have footage. It was very strange. @wbpictures... you just sold one more ticket."
However, despite numerous sightings it seems as though whoever is behind the Joker mask wants to keep his identity top secret.Featured Image Credit: Jam Press