This film had promise from the trailer (albeit with a story lacking any sense of originality but that's fine - sometimes we just want a good shark film).
The strength in this film is with how it doesn't show the shark to start with, other than a fin. A page taken from Jaws' playbook but, when that fin "looks" to do a handbrake turn when the shark senses blood, we know we're in trouble and everything is about to go downhill... And it does.
The over head shots of the shark in the water are okay but the constant - shark lunging for victim - shots are some of the worst CGI I've seen. But this isn't the worst thing about this film. That "accolade" goes to the acting and stupid script.
Example of script:
Women in water, shark circling them. They panic (fair).
One of them cracks a "joke" about dying from a shark attack in Manchester due to global warming. The women start to laugh whole-heartedly. THERE IS A SHARK CIRCLING YOU AND ONE OF YOU IS BLEEDING TO DEATH!!!!
I could say more but honestly, I'm annoying I wasted 86 minutes of my life on this. Give it a skip and remember the name of those who made this atrocity so you can avoid future work too. It's THAT bad.