More shallow than The Shallows, and lacking the depth of even Deep Blue Sea, this has chuckle-worthy moments but will be forgotten roughly 47 metres down in the lower-echelons of shark cinema.

Nothing in Thrash is going to wow Steven Spielberg, and its adherence to plot logic is elastic to say the least. But as bloody, dumb shark thrillers go, it stays afloat.

This is a Netflix and Chomp movie, just 80 minutes long (if you don’t count the closing credits), and the compact run time does more than keep “Thrash” from wearing out its welcome.

While we've seen almost all of this before there are enough well-timed scares to hold the interest even when things get silly.