The Shallows (apart from an ending that nearly makes the entire film shit the bed) is a hair-raising, beautifully executed and performed thriller that likes to remind the audience why going in the water's cool, but if you swim near a Shark's food, "you done f*cked up."

Blake Lively stars as Nancy, a physician in training who has taken an indefinite gap year for some soul searching. One-stop on this pilgrimage is a secret beach pictured in a photograph from her now-departed mother's youth. When she finds it, she waxes her board and shreds the picturesque break. During her surf, Nancy accidentally stumbles on the carcass of a whale and the cove's great white inhabitant sees her (and from that moment everyone around) as a threat and takes a nibble. Stranded on an exposed rock shelf thanks to the tide; the injured Nancy must calculate how to survive before the tide comes in.

Blake Lively is at her very best in The Shallows. She gets an opportunity to show emotional range and determination in the face of the mind-bogglingly terrifying odds. The physical performance she conjures to show the quickening effects of the life-threatening injuries is some of her best work. You can almost feel your own limbs aching watching her conduct DIY surgery.  With only a Seagull to play off of, it's a remarkably engaging performance

Director Jaume Collet-Serra wants you up close and personal with Nancy here. At the beginning of the film, some may see it as a kind of ogling of her physical specimen; but as the film progresses you're forced to endure Nancy's improvised medical procedures. Pressure bandages rigged from torn-off arms of her wet suit and staples fashioned from jewellery are administered to authentic grisly injuries with the same unerring focus. Screenwriter Anthony Jaswinski does a good job in the opening stanza of the film to add a bit of poetry to the popcorn thriller and allow Lively to convey the emotional necessity and spiritual fulfilment of this destination and riding that same break that her mother looked upon decades earlier.

You can almost see some completely misguided executive saying that Nancy's peril wasn't terrifying enough and Jaswinski and Collet-Serra pick up the discarded ideas (which won't be spoiled by this review) and thew them in; no matter how implausible or ridiculous.

The Shallows is completely worthwhile viewing, but it should have been a genre classic.

Score: 3/5

Blake Howard follow Blake on Twitter here: @blakeisbatman