Percy could discover ancient and forgotten temples or shrines in the wild. These could hold powerful artifacts or be the lairs of minor gods or spirits. He might have to face various traps and puzzles to explore them fully. In the process, he would rely on his skills as a demigod, like his ability to control water, to overcome obstacles and uncover secrets. This would be an exciting addition to the fanfiction as it would add new elements to the Percy Jackson universe.
In the wild, Percy might have to learn to survive without the conveniences he's used to. He could struggle to find fresh water, build shelters, and hunt for food. This survival aspect would test his physical and mental strength. Maybe he would also form an alliance with some wild animals, using his special connection with them (since he's a son of Poseidon, he has a way with sea creatures, and this could extend to some land animals in the wild) to help him in his adventures.
In the fanfiction, living in the sea could give Percy a chance to explore the secrets of his water - related powers more deeply. He could learn to control the tides in a more precise way or communicate with the very essence of the ocean. He might also face challenges such as dealing with underwater magic that is different from what he's used to on land. There could be ancient sea spells that he has to decipher in order to save the sea from a dark force.
He could encounter rare mythical creatures that are only found in the deepest parts of the wild. For example, he might come across a group of centaurs who have a different culture compared to those he met before. These centaurs could teach him new survival skills and ancient lore.
Well, he could encounter unique mythical creatures that are specific to the woods. Maybe he'll find a hidden grove protected by dryads where he has to prove himself worthy to enter. It could also be that he discovers an ancient magic in the woods that helps him in his quests.
He could be involved in some really cool quests. Like finding some ancient artifact that's hidden deep within Olympus. He'd probably make new friends among the minor gods and goddesses. And of course, there would be the constant threat of some ancient evil trying to take over Olympus, and he'd be right in the middle of the fight to defend it.
He might discover new sea creatures that are unique to Atlantis. Maybe he'll find a hidden school of magic there, or encounter ancient sea gods who have been forgotten by the outside world.
One possibility is that he discovers an ancient, hidden grove that has a powerful magical spring. This spring could have the ability to heal any wound or grant temporary superhuman strength. Percy would then have to protect this grove from other forces that might want to use it for evil purposes.
His relationships with his friends from Camp Half - Blood might become strained as he's away from them for long periods. They could worry about him and feel left out of his new adventures.
He could have adventures with the local wildlife. Maybe he has a close encounter with a moose or a bear. Or he could be exploring the vast, icy landscapes and discover some hidden caves filled with ancient artifacts.
Well, he might discover new magical creatures unique to Atlantis. Maybe he'll form an alliance with some underwater beings to protect Atlantis from an unknown threat.
He could have adventures with local mythological creatures. Alaska has a rich Native American mythology, and Percy might encounter spirits like the Raven or the Bear. Maybe he'd find a hidden tribe that has been protected by a local water spirit, and he has to help them deal with some threat to their water source.