This is based on opinion. Please don't list it on a work's trope example list.
Nightmare Fuel / Deadliest Catch
At the end of the fourth episode of Season 2, the Aleutian Ballad takes a sixty foot rogue wave in the middle of a storm. It was a hard enough hit to knock the boat onto its side. The camera captured it all when the wave hits, knocking the camera loose, making interference. Then the camera pauses, the power goes out on the boat, while the camera lays there, the power flickers, and the viewer can hear numerous fishermen calling to each other constantly saying 'hello!' and 'are you okay!?'...and all the while it's during the end credits. It was a lot like something out of The Blair Witch Project or [REC]. Scary stuff.
Even worse was the wave the Wizard took in Season 5, especially considering most of the crew was severely injured. Captain Keith is seriously lucky he did not lose any of his crew, especially his brother, who was hurt the worst.
Seeing Phil with a giant "divot" in his head where his skull was removed and his brains (or something) bulging out against the skin is squicky enough, and then you realize that despite the successful surgery and his chipper attitude, it ultimately didn't save him....
Season 8 king crab season: Greenhorn Chris on the Wizard suddenly going into convulsions on the floor inside the crab boat. It's strongly suggested that he's going into shock. He eventually has to be medivac'd out. Thankfully, he survived, as revealed on After the Catch.
To some people with medical training, Chris's condition might seem to be a simple case of hyperventilation. However, he had complained of numbness and tingling in his arm before the convulsions started...which indicates that it could have been a heart attack. In fact, Chris himself said on "After the Catch" that he came damn close to having one during this whole ordeal. Pretty shocking, considering he's only 20-years-old, but not unheard of. In any case, Chris revealed during that "After the Catch" that what happened was a "total body shutdown."
Season 8 opilio season had several:
The Time Bandit was listing badly while trying to pull into dock, and nearly tipped over. Had they been listing much farther, the ship would likely have collided with the dock and sank.
The Wizard's pots, having been incompetently tied by Lynn, swaying and clanking ominously in the waves and looking about ready to crush the unfortunate soul walking by them at the wrong time.
The Wizard had a blackout in the middle of an ice floe, leaving them a sitting duck until they were able to fire up the backup generator.
The Wizard trying to get out of a harbor that's choked with ice a (apparently the result of a freak tsunami) when their engine overheats and giant waves are pushing them towards shore where the hulk of a wrecked ship sits as a warning. Keith, who put his brother in charge while he went home to rest, was very upset his brother didn't tell him about this immediately.
The Northwestern had an undetected slack tank (a tank partially filled with water) that compromised the stability of the vessel. They only avoided sinking because Edgar's intuition told him to look in the tank (which was about to be covered in pots). Eerily, this is what sank the Foremost, the Northwestern's predecessor captained by the Hansens' father.
During the June 26, 2012 After the Catch episode, Keith Coburn revealed that the 2012 opilio season was literally Nightmare Fuel for him — he had post-traumatic nightmares for three weeks after he got home from it.
Mike Vandervelt on the Kodiak had the tip of his ring finger cut off when his hand got caught between the launcher and a pot after he slipped clearing ice off deck.
The crewman on the processor "Alaska Junis" who got hit by a snapped cable in the head — to wit, that was almost a carbon copy of the hit Nick Mavar on the Northwestern took to the nose a season ago. That guy wasn't lucky enough.
Johnathan Hilstrand and the Time Bandit's crew at the start of Opies 2015, are dealing with a new hire, a salted veteran of the fishing grounds, keeps causing strife on boardnote Arguing with how the crew does things, making false accusations that some of the younger Hilstrands on deck are complacent due to the ship being part of their family, and generally wasting people's time with his antics.. After slapping a greenhorn in the face unprovoked, and causing more strife on deck, Johnathan gives him a dressing down. The guy decides to retaliate by making threats on camera about sabotaging the boat, such as throwing out of season crab into the tank to make the boat suffer a huge fine, to removing parts from the engines or causing an engine failure, generic "tear up this ship" threats, and even towards Captain Johnathan. It's bad enough that it forces the Time Bandit back to St. Paul harbor, and police are called keep an eye on things, if the now fired deckhand started getting violent as he's getting kicked off. The crew was clearly creeped out by the guy, whose clearly not all there in the head happily telling people he's going to sabotage their boat in the middle of the dangerous Bearing Sea, wondering how serious he was.
In Season 12, Sig suffered a heart attack while heading out to sea and had to be medevaced to Anchorage. After some tests, his doctor tells him that he suffered a "widowmaker": a heart attack so severe that it could have killed him. As Sig is looking for some good news, the doctor cuts him off and says that the damage is permanent and that he will be seeing a cardiologist for the rest of his life. What makes it seem worse is just how matter-of-fact, almost cheerful, the doctor is in telling Sig just how bad everything is.