A savvy and free-spirited surfer is abducted by a shark-obsessed serial killer. Held captive on his boat, she must figure out how to escape before he carries out a ritualistic feeding to the sharks below.
This movie contains 39 potentially triggering events.
I personally wouldn't call it excessive, as in you don't see any insides and most impacts are off screen. You see a floating head that had been eaten by sharks from the shoulders up. It looks like a plaster head.
Have to spoil to answer! So warning! Someone goes looking after for the missing girl. He tries to save her but putting himself in harms way. Also the missing girl asks to be killed instead of him.
There is absolutely on screen self harm.
SPOILERS
The main character breaks and bites off her thumb to escape handcuffs. There's enough build that you can look away when it happens.