• Nightmare Fuel
    • Since you can get attacked in Blue World, the game uses a rather unnerving siren to warn you of nearby sharks. You'll be rushing for your pulsar in no time.
    • Okeanos's Guardian. Oh, dear god, Okeanos's Guardian.
      • Even before that: "Uh, guys, where'd Hayako go? ... Gaston? ... Oceana, NOOOOOO!
    • Ship's Rest is bad enough just wandering around it at night, but then when you activate that cutscene... HolycrapwhatthehellisthatAUGHGETITAWAYBEFOREITEATSME!
    • These games might be tough for anyone with a fear of deep water and/or darkness. Swimming out into the open and then looking straight down is not a wise decision if that sounds like you. The abyssal zones are just as bad - the one in the second game a bit less so, with a bit more light and less open space.
      • Fortunately, this also means they can act as a form of therapy.
    • Just about anything big that attacks you in the sequel (mostly sharks). Thanatos and the Okeanos Guardian definitely qualify as nightmare fuel. It gets even worse when you explore their respective dive spots at night.
    • A cut scene triggered in the Triton Village (again, at night). You see this massive shark silhouette slowly approach you from behind at the Triton Village entrance, and it only turns out to be a harmless basking shark.
    • It can be very unnerving to be swimming in deep water or at night and have one of the larger creatures suddenly appear out of nowhere. This particular troper was exploring down around the lower cliffs in the Zahhab Region, and turned around to find herself face-to-face with Leviathan. He won't hurt you, but it's still enough to make one jump.
      • The abyssal zone in the first game is notorious for this, being pretty much pitch-black and with a fairly large open area between the cliffs. Often, the sperm whale and the giant squid will pop out of the darkness unexpectedly, which can be jarring even if you were looking for them.
  • Crowning Moment of Awesome: See Screw the Money, I Have Rules. Also, discovering the Ancient Mother, intersecting with both Crowning Moment of Heartwarming and Tear Jerker.
  • Crowning Moment of Heartwarming: Blue World contains little cutscenes that can be viewed by swimming into the right area during the right conditions (time of day, weather, etc.). Among them are scenes of a mother caiman caring for its young, manta rays partaking in a courtship dance, monk seals laying around acting all cute, and green turtles laying their eggs and their subsequent hatching.
  • Even Better Sequel: Blue World addresses several complaints about the first Endless Ocean and sacrifices very little in the process.
  • Scenery Gorn: Most of Ship's Rest.
  • Scenery Porn: Most of the earlier areas, and some of the later ones (see: the White Room in Great Aqua Cave.)
  • Tear Jerker: Kat's backstory, and the secret cutscene unlocked by sitting on the deckchair at sunset. The cutscene when you find the Ancient Mother is more of a "tears of joy" example.
    • And then, in Blue World... Jean-Eric's son (and Oceana's father) Matthias became trapped in his submersible 650 feet down in the Zahhab Depths while researching the Song of Dragons; he died attempting to escape and left a message for his father in a waterproof case explaining why his work was important to him and that he loved his family very much, giving his old man something to shoot for once more.
    • Sidequests heavily imply that Matthias is still alive but the plot thread is never fully resolved.
  • Ugly Cute: Lots of the fish are pretty in really bizarre ways.
    • Even an In Universe example, as Oceana squeals over many of them.
  • The Woobie: Kat.