u/PringlesTuna

I remember seeing a beach themed mod a couple years back, and the new aquatic pack is veeeeery similar to the mod in many ways.

https://www.reddit.com/r/Oxygennotincluded/comments/1fvvb4l/making_a_mod_for_a_beach_biome_start/

Some of the assets and art are literally the same. There's no way this is not some sort of collab at the very least. The Binding of Isaac did something similar with Afterbirth.

Edit: "We teamed up with long-time ONI modder Aki on parts of this DLC, which makes it extra special for all of us." - forum post by Klein, thank you u/gbroon for pointing this out.