These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Hilarious in Hindsight: It becomes even harder to take Adrift seriously when you realize that an episode of King of the Hill used the exact same plot as the movie, except the setup was played for its inherent comedic value rather than drama.
Tear Jerker: James getting progressively worse as Adrift goes along and his wife singing "Frère Jacques" softly after he dies the way he did for her when she was in a catatonic state of panic. Especially painful because he was the only halfway smart guy in the film before he got that crack on the skull.
James telling his wife not to cry.
Susan begging Daniel not to die and "leave me out here all by myself". Susan realizing that Daniel has died and letting his body go, then turning away as the sharks take him. Susan finally giving up and sinking beneath the surface.
Sequelitis: It has a sequel, called Adrift, which is very different from Open Water. It only retains the fact of people being stuck at sea.
Ofcourse it can not fully count as this, considering it was only chosen to be a sequel to the movie after the whole thing was made, because they thought the idea was too similar to stand on its own without being considered a rip-off.
What an Idiot: The people on the boat, both in the movie and in real life.