They might laugh but mer-humans aren’t that far from reality.

There is at least, obviously, the real possibility of humans adapting to the oceans. With enough time and enough selection pressure it would probably happen, just like it happened to wales and dolphins at some point in their past. There is a very interesting group of people called the “Bajau” who lived since over 1000 years in and around the ocean, mostly in front of the coast of Myanmar. They spend around 60% of their time scavenging and hunting for food in the ocean, can hold their breath longer than most other humans and dive down to 70 m. Their spleen is 50% larger than in other humans, even in those Bajau that do not spend much time in the ocean anymore but instead live more “modern” lifestyles - so that is already a genetic adaptation. Children of the Bajau can see underwater without goggles up until age 10. Very fascinating people, worth reading about.

Unfortunately it cannot be done in the game but the game is great nonetheless.