Honest to God I went into this assuming it was gonna be a bad movie, but I was actually wrong. Yes, it's my opinion, and people are gonna have different beliefs about the quality of the movie and whatnot, that's fine, but I personally really enjoyed it.
Listen, the CGI is God awful. Seriously disgusting. The sharks looked like something I made in art class.
Having said that, the sharks don't add or take away much from the story. Tiny spoiler, the sharks aren't the only danger. There's also strong ocean currents and limited supply of oxygen, which is part of why I enjoyed the film so much. It wasn't just another shark movie, there were many other aspects to it that I thought were well thought out.
Another thing I enjoyed, tiny spoiler, is that there are so many opportunities for them to escape but they never can until the very end. At first this sounds cliche and like every other "get out alive" movie, but every way they could've escaped is creative and clever. It isn't just, 'oh, let's swim this way and then we should get out'. There's the original tunnel, following a red wire to an exit (I forgot the actual name), a hidden grove area thing they tried to climb out of, a tunnel hidden in strong ocean currents that leads out to the ocean, and then right at the very end you think they're safe but they're actually right at the site of the glass bottom boat tour from the very beginning that attracts even more sharks than were in the cave. That was such a good circle ending, I think it was so clever, I loved it.
So, yeah. The CGI is really bad and so is some of the voice acting (I'm assuming that's what it was, it sounded like they were talking into a microphone at certain points), but I still really enjoyed it. If I could I would give it 8.5/10, but since we're on a scale of 5 I'll just give it 5/5.