A novel by author Nancy Farmer [[XMeetsY combining]] historical fiction with {{fantasy}} about a Bard's apprentice living in a village on the coast of England in TheLowMiddleAges. The [[DoomedHometown said village is invaded]] by Vikings, who capture him as a slave. He survives captivity by demonstrating his recently-developed magical bard powers and making himself useful to the Vikings.

In the Norse town where he ends up, events transpire which lead him to accompanying several warriors on a quest into Jotunheim, the land of the [[AllTrollsAreDifferent Trolls.]]

Nancy Farmer later wrote two sequels, ''Land of the Silver Apples'' and ''The Islands of the Blessed''.

Despite the title, no apparent connection to [[{{Imageboards}} 4Chan]] and Website/SomethingAwful.
!! ''The Sea of Trolls'' and its sequels provide examples of the following tropes:
* AllMythsAreTrue
* AllTrollsAreDifferent
* BeautyEqualsGoodness: Specifically subverted with Pega and Thorgil, as Jack notes that even though Pega is hideous she has a good heart and beautiful voice, and Thorgil's bad temper negates her natural beauty.
* BelligerentSexualTension: Thorgil and Jack, by the third book.
* TheBerserker: Lots of literal berserkers (actual Vikings) appear in these books.
* BrokeYourArmPunchingOutCthulhu: [[spoiler: In the second book, Thorgil [[SugarWiki/MomentOfAwesome punches Satan in the face]], but her hand becomes paralyzed because of it.]]
* ConfusionFu / InsanityImmunity: {{Berserker}}s are immune to trolls' mind-reading powers because their mindless, frenzied style of fighting is impossible for the trolls to decipher.
* TheDeterminator: Thorgil. Full stop.
* {{Disabled Love Interest}}/{{Disabled Snarker}}: [[spoiler:Thorgil becomes these after punching {{Satan}} in the face, which leaves her right hand paralyzed.]]
* DoomedHometown
* EldritchAbomination: A few appear, including one who appears to be {{Satan}}. (At least, that's what a Christian would call him. People from other religions see him differently; for example, Thorgil sees him as the HellHound Garm.)
* EveryoneCallsHimBarkeep: The Bard.
* TheFairFolk: Elves in general, but they ''are'' capable of doing a HeelFaceTurn and gaining a soul.
* FishPeople: Mature fin folk.
* HellHound: How Thorgil sees {{Satan}}.
* [[spoiler:TheHeroDies]]
* HeroicFantasy
* HereThereWereDragons: In Jotunheim, however, they're still thriving.
* HistoricalDomainCharacter: King Olaf.
* LadyLooksLikeADude: Deconstructed right down to the bone with one character.
* TheLowMiddleAges
* MadeASlave
* MentorOccupationalHazard: [[spoiler:Seemingly played straight, then averted in a TwistEnding. The Bard was not dead. He was actually disguised as a bird all along.]]
** [[spoiler:He actually does die in Book 3.]]
* NakedPeopleAreFunny: Freya's cats naked and Frith naked. Also counts as {{Squick}}. Averted with Rune, whose nudity in his introduction is described tragically.
* NorseByNorsewest
* TheObiWan: The Bard
* OurDemonsAreDifferent
* OurElvesAreBetter: They're of TheFairFolk variety. They're also way different from other fictional elves in that [[spoiler:without their glamour, they look like ugly monsters.]]
* OurDragonsAreDifferent: They live in cliffside caves and raise their young like birds. Their blood can even give you the ability to understand bird-language, as per the myth of [[Literature/VolsungaSaga Sigurd and Fafnir.]]
* OurMermaidsAreDifferent: Young merfolk look like the classic "good-looking-human-with-a-fish-tail" variety, but as they mature they turn into FishPeople.
* PsychicPowers: Lots of characters have PsychicPowers, including trolls.
* {{Satan}}: He makes an appearance near the end of ''The Land of the Silver Apples.''
* SpeaksFluentAnimal: Halfway through ''Sea of Trolls'', Thorgil [[IncrediblyLamePun swallows]] dragon blood, giving her the ability to speak bird.
* TheTimeOfMyths
* TheWorldTree