Sometimes, when I have a little time to kill, I browse Netflix (or some other streaming service) in search of something I wouldn't ordinarily watch. Sometimes, that leads me to nature-gone-wild thrillers, usually involving sharks, crocs or gators. Today, I found sharks.

The premise of 47 Meters Down is interesting enough. Sisters Lisa (Mandy Moore) and Kate (Claire Holt) are vacationing in sunny Mexico. Lisa is trying to get over a bad breakup (many details of which apparently were filmed and, thankfully, left on the cutting room floor), so her younger, more adventurous sister talks her into a night of drinking, dancing and flirting, followed by a deep-sea cruise and scuba dive in a shark tank. What could be more fun?

The boat is captained by the affable Captain Taylor (Matthew Modine) and crewed by the slightly mean-spirited Javier (Chris Johnson). The two Mexican paramours, Louis (Yani Gellman) and Benjamin (Santiago Segura), go down first and, thanks to some illicit chumming, see some mighty big sharks. Great whites, of course, because that's what always shows up in movies. Then it's the ladies' turn. Of course, things go awry.

Although their shark tank is only supposed to go down about five meters, Lisa panics shortly after seeing her first pair of sharks and feeling the cage slip a bit on its cable. She pleads to be brought up immediately, so Taylor starts the winch ... but, of course, the cable snaps and the cage plummets to the sea bed, exactly -- you guessed it -- 47 meters down. They don't have a lot of air, and that's too far to swim without getting the bends, especially when there are sharks in the water.

So, what will they do?

Panic, mostly.

I don't know enough about deepwater scuba diving to debate the facts with filmmakers, although some online experts say the air lasted longer than it should have, their eardrums should have burst in the fall from rapidly increasing pressure, and they shouldn't be able to hear on their radios while under water. Oh, and some issues with the tank regulators and technicalities with decompression and ... well, I leave that to the experts, who are free to pick apart the details to their hearts' content. A certain suspension of disbelief is always required in the world of cinema, and in this case I'm not going looking for nits to pick. I mean, this is a shark attack movie, and we're already dealing with sharks who are unusually large and are acting outside of their normal behavior patterns.

So, as a non expert, how did I like it? It's ... fair. There is way too much talking, especially when the sisters are trying to conserve their air. While I can buy one cable snapping to set up the plot, a second one strains credulity -- even in a monster shark movie -- as does the last-second timing on both sisters' air tanks. (Taylor's explanation for not sending spare tanks down to them sooner also rings hollow; he's willing to risk their deaths by asphyxiation because he's afraid they might die of nitrogen poisoning?)

On the other hand, the movie provides a couple of good jump scares. Even better, it really evokes a sense of claustrophobia and dread down in the dark and cloudy depths that make things very tense. That is very well done, and I imagine on the big screen it is even more effective.

On the other other hand, I didn't like the ending. While I appreciate an unexpected twist, this one has two -- the first I didn't love, but it seemed legitimate, given the circumstances, but the second felt dishonest on the part of the screenwriter and director, misleading the audience just to get an emotional reaction and add a few thrills to the climax. And then everything is over, roll the credits, abruptly.

At the end of the day, 47 Meters Down isn't a terrible shark movie, but it isn't great, either. I enjoyed parts, and sometimes I found myself glancing at the time. I don't expect I'll ever want to watch it again, nor will I probably recommend it to a friend. Basically, if you have some time to kill, it's available on your streaming service and you like shark movies, well, here's one.