My friends and I were messing around in the swamp and found a little bug with pushing. I was standing next to the edge of the water and a swift push revealed that you could indeed go down to the bottom. After a few moments of trying, the rest of my squad was able to leap down and join me. Could only move via jump, and there wasn't much down there, but I thought I should post it here with some pictures.

This is the map location
https://drive.google.com/file/d/1vU_EMguSSUJaeLcc_leiOQfxLhoGxIn8/view?usp=sharing

This is the location that you can jump into
https://drive.google.com/file/d/1djh9HIzhW618lORY3nZIsYvI_MLBj7Hk/view?usp=sharing

and here are some assorted pictures of me and my goons frolicking on the sea floor
https://drive.google.com/file/d/1pYxRk8lYeNzh8bFtc9H9EJqIrwmVStQV/view?usp=sharing
https://drive.google.com/file/d/1gIOC2xoVnEYyKJNL6hkzZdMbO9wwvV3q/view?usp=sharing
https://drive.google.com/file/d/1BrZFT-w123z0CaVTj3WcrBKRrNjSJGRS/view?usp=sharing

Its not necessarily a game play issue, but I'd wager accessing this area was unintended (at least without some 3rd level spells lol)