The MC could become a penguin by accidentally entering a forbidden area or getting involved with绁炵 powers. Challenges? Well, there could be problems like not being able to move fast on land or struggling to fit in with the penguin community.
One potential enemy could be developers. They might see the hot spring as just a piece of land to build on, not caring about the mc's new existence as the hot spring. Another could be rival natural attractions. If there are other hot springs or beautiful places nearby, they might be jealous of the mc's hot spring getting all the attention and try to undermine it in some way.
Well, it could be about the main character who is reincarnated as a hot spring. Maybe they can communicate with those who come to soak in them, like sharing the stories of their past lives or giving out some mysterious advice. And there might be some sort of adventure as the hot spring tries to protect its existence from those who want to develop the area or something like that.
There are several. One example could be 'The Reborn Hero's Love for the General', where the MC reincarnates and develops a deep affection for the general.
Sometimes it's good for a reincarnated person to be OP. It can lead to unique plot developments and show their dominance in a new world. But too much power can also make the story less interesting if there's no real struggle.
Often, these mangas feature the boy gaining new powers or abilities in his reincarnation. The story might also focus on his growth and adaptation to the new world.