Based on real events, Open Water is the story of two vacationers who become stranded in shark infested waters after a mistake during a SCUBA diving trip. When reading the back of the box, the plot is pretty interesting, especially considering the movie's main element is a true story. Once you begin watching, much of the plot's luster is lost.
The movie's biggest flaw is that its main characters, Susan and Daniel, are unlikable. In order for a horror movie to work, no matter what type of scare you're going for, you have to care for the characters or at least care what happens to them. From the start of the movie, I found the characters to be a pair of self-absorbed jerks.
If the point of the movie's setup was to show how self-absorbed the two were (they even complained about too many people being on the scuba trip), then the writer did a great job. Both are completely wrapped up with their jobs and don't even seem like that close of a couple. It's as if they're together just because it's what you're supposed to do. The chemistry between the two is barely there. Even a montage of the couple having "fun" on their vacation feels stiff and forced. A frigid 'non' bedroom scene that seemed like it was thrown in to show off frontal nudity caps off the lack of chemistry.
In transition to the couple's predicament, there's never a part where you begin to like the characters. Dialog remains stiff between the two, even when trying to inject some 'comic relief'. The tour guide screwing up the head count and the fact that no one on the boat realizes the couple is gone come off as comical. I actually found myself saying that the couple deserved it. Once in the water, the two become even less likeable, and I actually found myself on the side of the sharks.
Open Water has all the markings of an independent film. The cast is full of complete unknowns, and the movie could have easily been filmed by anyone while a high-priced digital camcorder. This gives the movie a more 'personal' feel to it - which I found helped keep me from turning off the movie, something I was tempted to do at several points thanks to the stiff dialog and lifeless characters.
As far as extras, Open Water isn't as robust as a DVD release (which is to be expected), but manages to squeeze in a short movie of the director swimming with sharks. Like the movie it is attached to, the sequence sounds better than it is. If you're someone who enjoys watching other people's vacation videos, you may enjoy this.
Had the characters' chemistry been better, Open Water probably would have turned out to be a better movie. The plot is interesting enough to warrant a look, but when you start to laugh at their predicament, something isn't working.