The Brown Island is a land that can only be found on the Ocean. It has 4 altitude levels, and monsters (with the exception of birds) can't climb 2 or more levels or descend 3 levels. Since the Brown Islands do not have a visible boundary, they may be difficult to find from the Ocean; but they can be found by tracking where Acid Gulls fly from.
Brown Islands have two parts: a big region with elevations 0-3 with a diameter of 10-20 tiles, and a strip region, which is for the most part one block wide. That's because it was made by a Random Walk algorithm, that moves randomly, and reproduces infinitely. (a video about that).
When an Acid Gull is killed, it will reduce the altitude level of its tile by 1. Tiles at ground level will become water. Bronze Beasts cannot be killed directly, although they can be stunned and pushed. If they fall more than 3 altitude levels or fall into water, they will die, increasing the altitude level by 1. Because killing the Bronze Beast lifts the altitude level by 1, it is possible that the Brown Island is made of Bronze.
Monsters[]
Acid Gull
Bronze Beast