* AccidentalAesop: The villagers do ''not'' take kindly to outsiders, to the point that they're worse than the disgusted visitors are. This brings an unintentional "discrimination is a two-way street" message to the story.
* CompleteMonster: Obed Marsh, the founder of the [[{{Cult}} Esoteric Order of Dagon]], was a sea captain who observed foreign tribes achieve prosperity by [[HumanSacrifice sacrificing human beings]] to the aquatic [[FishPeople Deep Ones]]. Taking the practice to his [[DyingTown dying hometown]] of Innsmouth, Obed proceeded to institute mass sacrifices until his first mate led a rebellion against him. Rallying his followers, Obed slaughtered half the town and instituted a new regime of tyranny and murder, with many forced to [[FaceFullOfAlienWingWong breed with the Deep Ones]] in a horrific practice that lasted nearly a century.
* FridgeHorror:
** The narrator spots "some bulky, tarpaulin-covered object" on a rowboat while [[spoiler:escaping from the town, and when the government men went there, they never found Zadok Allen]]. [[HeKnowsTooMuch The implications are obvious]].
** One has to wonder what would've happened to that cashier had Robert not come to Innsmouth...
%%-->"Obed he kinder takes charge an' says things is goin' to be changed ... others'll worship with us at meetin'-time, an' sarten haouses hez got to entertin guests. . ."
* HarsherInHindsight:
** From the story (keep in mind this was written 70 years before Gitmo and UsefulNotes/TheWarOnTerror and, more disturbingly, only several years before UsefulNotes/TheHolocaust and the internment of Japanese-Americans):
--->"Keener news-followers, however, wondered at the prodigious number of arrests, the abnormally large force of men used in making them, and the secrecy surrounding the disposal of the prisoners. No trials, or even definite charges were reported; nor were any of the captives seen thereafter in the regular gaols of the nation. There were vague statements about disease and concentration camps, and later about dispersal in various naval and military prisons, but nothing positive ever developed. Innsmouth itself was left almost depopulated, and it is even now only beginning to show signs of a sluggishly revived existence."
** This becomes especially bad when one remembers that the symbol the Pacific Islanders used to ward away the Deep Ones was a [[UsefulNotes/NonNaziSwastika swastika]].
** Lovecraft was likely aware of the Palmer Raids just after WWI, in which the federal government arrested and deported hundreds of foreign-born radicals without due process.
** The story may also draw inspiration from the Red Summer of 1919 (which occurred at the same time as the Palmer Raids), when dozens of black and mixed communities were attacked and massacred by white mobs from Connecticut to Oklahoma.
* NauseaFuel:
** They interbred with ''slimy, ugly fish-frogs from the Stygian depths of the sea!''
** The air of Innsmouth is usually described as having a pungent stench of rotting fish.
* NightmareFuel: The sequence in which the protagonist is pursued through the town at night by its residence from his hotel room all the way to the surrounding roads, hiding in crumbling houses that contain unseen horrors and praying the townspeople's car headlights don't find him, is one of the most harrowing {{chase scene}}s in literature, and a triumph from an author who largely avoided action scenes.
* OnceOriginalNowCommon: [[HillbillyHorrors Hillbilly Horror]] plots involving [[TownWithADarkSecret isolated enclaves]] of mutant/interbred hicks with ill intentions towards the outsider protagonist have since been done to death. Ditto fish people.
* ValuesDissonance: The implied message, "Race mixing is A Bad Thing", is less acceptable in polite society nowadays than when Lovecraft was writing.
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