I realize that this idea is actually very, very stupid but it's fun so why not? :) Percy Jackson has become...THE LITTLE MERMAID! Er... merman? So, obviously there will be elements of both stories here, but I'm going to give a character run down so you don't get too confused.
Percy: Ariel
Annabeth: Eric
Grover: Grimsby
Tyson: Flounder
Chiron: Sebastian
Poseidon: King Triton

The sun shone brightly down on the ship sailing leisurely across the sea. Sailors worked tirelessly, heaving ropes on the deck. They sang as they worked, in deep baritones,

"I'll tell you a tale of the bottomless blue

And it's hey to the starboard, heave ho

Look out, lad, a mermaid be waitin' for you

In mysterious fathoms below."

One blonde haired woman rushed back and forth, a wide grin on her face. She leaned over the side of the ship and looked down at the shimmering water. She took a deep breath and then said,

"Isn't this great? The salty sea air, the wind blowing in your face . . . a perfect day to be at sea!"

A man with curly hair leaned up from over the side of the ship, his face green.

" Oh yes . . . delightful . . . ."

"Cheer up Grover!" the woman said with a laugh.

A sailor looked over and grinned, gold teeth glinting behind his gums.

" A fine strong wind and a following sea. Poseidon must be in a friendly-type mood."

"Poseidon?" the young woman said, raising an eye brow.

"Why, god of the sea and ruler of the mer-people, lass. Thought every good sailor knew about him."

" Merpeople! Annabeth, pay no attention to this nautical nonsense!" Grover interrupted, holding a handkerchief to his mouth.

Another sailor looked up from piling fish board and said,

"But it ain't nonsense, it's the truth! I'm tellin' you, down in the depths o' the ocean they live!"

He gestured wildly as he said this and the fish slipped from his grasp. It hit Grover full in the face and then fell back towards the ocean. Annabeth watched it go with a smile. She was happy that it got away, got to return where it belonged.

"Heave. ho. Heave, ho. In mysterious fathoms below" she sang to herself, looked at the dark depths.

Sorry it's so short, the next chapters will be longer and better, I promise!