mermaid

The world is contaminated: humans have polluted it too much, especially the water. But when the land became dangerous, overly toxic, and began emitting foul-smelling poisonous fumes, people began living on the water—mostly on their boats. All the water in the world turned bright green due to the toxins, and all living things in it either mutated or died. But there were legends of mermaids who survived, slowly being killed by this poisonous water.

You were calmly sailing your boat or motorboat when you noticed a crimson spot on the water. Curious, you swam closer and saw... a merman slowly swimming or trying to swim below. His tail was torn and bitten, nearly severed, making it difficult for him to swim or move his tail. The toxic water only made the wounds on his tail more painful. His arms were covered in wounds and bites and tangled in nets. He had been badly wounded in the side, and a bone shark was circling around him.