Shinobi of the High Seas

Shinobi of the High Seas by Kenchi618 is a Crossover fanfic between Naruto and One Piece that takes a rather cliche and overdone idea and takes it in a completely different direction than expected, resulting in something both original and highly awesome.

The story's premise is that a semi-immortal Naruto, many many years after ending the Fourth Shinobi War and bringing peace to the Elemental Nations, decides that there is no longer any place for him there and sets out on a small merchant's ship to explore the world. After running into and capturing a pirate crew, he sails to a small town to collect the bounties, he finds the town empty save for a lone dog in front of a pet shop and a strange ship similar to a carousel...

While most crossovers simply just have Naruto join Luffy's crew from some point in the orginal manga's storyline--in this case, the Buggy arc--the author of this fic tries something different. While Naruto does travel with Luffy at first (Luffy calls him his ships' resident hobo), he soon splits off and gets his own ship(which is orange, of course) and crew (which consists of main characters from certain arcs of One Piece) together to enter then Grand Line. While he does come across Luffy and Crew during some of the more major plot points (such as Alabasta), Naruto and his crew have their own adventures, running into many familiar faces from the One Piece-verse along the way.

It should be noted that, while Naruto is essentially a Gary Stu in this fic, being both semi-immortal and much more powerful than the majority of characters in the fic, this is one of the very few fanfics out there that actually does the concept right. Naruto does not simply jump in to every single fight and leave the others to just stand and watch, nor does he handle every enemy with no effort whatsoever.

The story is currently just past in the "Shabondy Archipelago" arc and 41 chapters in, and is easily one of the best crossover fics out there. It can be found here.

Tropes used in Shinobi of the High Seas include:

A God Am I: Naruto hates being refereed to like this.
Action Girl: Nojiko, Miss Valentine, and Vivi, due to Naruto's relentless training. And then Vivi is hit with the Distress Ball.
Badass Crew: And how!
Badass Grandpa: One could argue that Naruto is this, given his age...
Badass Teacher: Johnny and Yosaku feel this way about Naruto, becoming his first crew members because they want him to train them to be stronger.
Berserk Button: Naruto finally finds someone who knows how to make ramen during the C9 Arc. Only problem is...
Catch Phrase: Naruto finds himself exclaiming "dattebyo!" multiple times over the course of his travels, despite the fact it's both been years since he's used it and that it seems to annoy him as well. I guess some things just become ingrained no matter how much time passes.
Confusion Fu: Naruto's a big fan and believer in fighting this way.
Curb Stomp Battle: All of Naruto's fights pre-Grand Line are this, most especially against the Arlong Pirates. Once in the Grand Line though, he doesn't have it as easy. Eventually he has to use the Hiraishin, Sage Mode, and the Rinnegan.
Dynamic Entry: Naruto pulls of the Maito Gai version of this, complete with "Power of Youth" shout. He is understandably unsettled about the latter, afterward.
Early-Bird Cameo: Naruto & Crew come across Boa Hancock much earlier in than Luffy did in the series.
- Kizaru arrives at the end of Alabasta to go after Naruto. And again after successfully rescuing Vivi and stopping the slave auctions.
Elephant in the Living Room: A literal case, in which Naruto gives his ship's doctor, Muret Spandam's sword Funkfreed. For those of you unfamiliar with One Piece, that's a sword that can turn into a freaking elephant!
Embarrassing Nickname: Miss Valentine is too fond of the nickname given to her by the Marines: "Human Albatross".
Even Evil Has Standards: Even Kidd is disgusted with the slave auctions. Keep in mind, this is a guy who killed everyone on an entire island because they laughed at him.
Fragile Speedster: Thanks to Naruto, Johnny has become ridiculously fast.
Gary Stu: As mentioned in the description, Naruto is a total Gary Stu in this story. There is literally no point in arguing against that, because it's just so blatant. But despite this, the story somehow manages to be pretty good.
- It helps that, aside from a couple new jutsu, this is basically the same Naruto from the current part of the manga, just much older and more experienced.
Gun Slinger: Nojiko becomes this thanks to Naruto's training.
Heroic Sacrifice: A non-death example. Naruto gave up living in Konoha, staying with his precious people and his dream of being Hokage to become a wandering hermit to keep the peace between villages, given that Naruto was the hero of the Fourth Shinobi War and the most powerful ninja around.
I Want My Friends To Be Happy: Naruto essentially lives and breaths this trope for his crew; it's just been a long time since he's had people to care about.
Mass "Oh Crap": Naruto's crew when Kizaru suddenly warps smack dap on the middle of the ship.
Mighty Glacier: Yosaku isn't very fast but he casually swings a 4 ton hammer for training.
Nakama: Goes without saying, really. Even the members of Naruto's crew that were somewhat forced to join admit they care about the others after awhile.
Names to Run Away From Really Fast: Where to begin...
- "Armory Mistress" Nojiko
- "Lord of Iaijutsu" Johnny
- "Cleaver" Yosaku
- "Human Albatross" Miss Valentine
- "The Plague" Soren
- And last but not least: "Seed of War"/"God Sage of Anarchy" Uzumaki Naruto
Oblivious to Love: Suprisingly averted, given the character in question. Naruto is fully aware when one of the girls likes him for the most part. He just plays dumb until they are actually up front with him about it.
Older Than He Looks: Naruto, obviously, though its recently been revealed that he's only about 90 and not over 120 like he's been saying. Turns out he was just bored of keeping track.

Naruto: "Keeping track of time is useless if I can't die of old age. I forgot. I might as well be older. It doesn't matter, what's the difference? Old is old."

Oh Crap: Naruto's crew, anytime their captain wants them to learn something. See Training from Hell below.
Poisonous Person: Soren the Plague can turn any of his body fluids into acid.
Protectorate: C'mon, he wouldn't be Naruto if he wasn't like this to his precious people.
Shout-Out: Naruto wants Nojiko to learn how to bend bullets.
Running Gag: For the last time, Naruto is not a pirate!
- Naruto's quest to find someone who knows how to make Ramen.
Tenchi Solution: Seems to be headed toward Type-2.
Took a Level in Badass: All of Naruto's crew are much strong than their canon counterparts, thanks to Naruto's relentless training regiment.
Training from Hell: Naruto rountienly increases Johnny and Yosaku's chakra weights, given to them to incease their speed and strength, whenever they adjust to the added weight...and to punish them....and to teach them something... and whenever he feels like it...
Tranquil Fury: Naruto reaches this after hearing everything Arlong put Nami through. The results ain't pretty.
Wanted Poster: Naruto is fairly indifferent when he sees his first wanted poster, save for that he's given the nickname "Seed of War". His second poster and nickname "God Sage of Anarchy", on the other hand...
War Is Hell: Naruto spent the better part of a century bringing peace to the Elemental Nations, and he's not going to to let anyone mess with that, least of all the World Government.
Weaksauce Weakness: Kizaru has been beaten twice by using a mirror to reflect him away.
Who Wants to Live Forever??: While Naruto isn't too overly angsty about all his friends and loved ones having long since passed on, he does come to realize how boring being immortal is.

Naruto (literally the first line of the fic): "*sigh* Boooreddddddddaaaaa!"

World of Badass: To such an extent that in chapter 41, Naruto decides he's going to need Kurama's help if he wants to continue sailing.