Kristen Stewart is working in an underwater facility when it all goes horribly wrong.

Oh no all the escape pods are taken so the survivors will have to don diving suits, catch a lift to the bottom of the ocean and walk home. It should be fine as long as the waters aren't filled with some nasty monsters released by the drilling. whoops!

The action is immediate and hard hitting and thrilling.

This has all the elements you can imagine, people getting stuck under things, oxygen running out, rooms filling with water, sea creatures mauling people etc. The effects are great, the monsters interesting and it is all done quite well.

"Quite well" is the problem. This film looks like it is going to be amazing and it is hard not to get excited about it. So when it takes a paddle around lake-mediocrity it feels really, really bad.

The characters are stark and relatable but you get no build up so you are always playing catch up with them and the relationships between them were a little unclear. Kristen Stewart's character has a sub plot that should be really meaningful but just feels tacked on as it is relayed through the mediums of chitchat and locker junk.

You get no feel of where the survivors are going so a lot of the plot relies on aptly placed road signs and a patronising version of Alexa, who is zero help to the crew, until it needs to explain how the film is going to end - which it does in patronising detail even drawing us a little picture.

This is a pretty good disaster/monster flick but it feels like a lot of potential has been wasted - which makes me think less of this film than I should.

The production and performances are all good. Kristen Stewart is very good, but maybe she is stereotyped in my eyes as it took me twenty minutes to shake the feeling that she was on her way to a Halloween party dressed as "the real slim shady" when this all kicked off.

A good enough movie but with a tiny bit more work and a little more nerve this would have easily been an absolute classic people were talking about for the next fifty years.