“The Shallows”

Rated PG-13 (1:27)

** 1/2

Opens Friday

Every summer needs a movie that’s as sun-drenched and easy-breezy as “The Shallows,” the Blake Lively vehicle that pits surfer vs. shark. On a triple digit day, you won’t be sorry to duck into this quick 87-minute caper of bikini-clad aquatic peril that’s just silly enough to be the perfect summer thriller. But this woman against nature tale is more than just escapism, as it’s got some great tips for any beach adventurer. Here are Top Five Tips for Battling Sharks From “The Shallows.”

1. Always surf with a buddy. Med school dropout Nancy Adams (Lively) takes off for a secretive Mexican beach without her hungover friend, because she has always wanted to experience the special secret spot beloved by her late mother. Surfing alone is never a good idea, especially when Nancy goes back for one more wave after the locals take off.

2. Make sure you have the right gear. Clad in bikini, wet suit top, sport watch and what seems like way too much jewelry, Nancy puts every single item to use in multiple different ways during her ordeal. Bit by a shark? Use that surf leash as a tourniquet, wet suit sleeve as compression bandage. And you’ll sure be glad for that very pointy pendant and earrings when it’s time to improvise some sutures, as gruesome as that might be (very).

3. You don’t have to be superhuman, just resourceful. Nancy, an athletic surfer and med student, isn’t a superhero. She makes some really dumb choices (paddling toward a bloody whale carcass being the worst offense), she’s not the most graceful swimmer, and she takes some serious risks when trying to get out of this oceanic conundrum. But she keeps her wits about her, pays attention, remembers details from the locals, carefully observes her environment and the creatures in it, and uses every scrap of everything she has, and every last bit of energy to outwit an insane shark that stalks her over the course of two days.

4. Make friends wherever you go. Nancy befriends Carlos (Oscar Jaenada) who gives her a ride, the local surfers, and even an adorable seagull named Steve. While she has to, and can, save herself, her emotional connections to the people and animals around her steel her fighting spirit and offer her comfort in the darkest moments.

5. You’re smarter than the shark. You can’t be faster than the shark, and you can’t be stronger than the shark. You can’t reason with the shark, especially when it’s angry and out to get all humans. So the only option is to outsmart the shark. Use physics.

Ultimately, “The Shallows” is a splash of fresh seawater in the face of a rather dismal summer movie season. It’s very cheesy, which is how escapist summer cinema should be, and part of its charm is that it’s not self-reflective enough to be aware of its own cheesiness. It also features the worst/best appearance of jellyfish as a climactic storytelling device since the movie “Seven Pounds” (thank you, writer Anthony Jaswinski).

But director Jaume Collet-Serra knows his genre thrills and builds layers of suspense and dread, along with some hypnotically beautiful aerial ocean shots. As a surfing movie, there’s not nearly enough action. As a shark movie, it’ll have you thinking twice about going back in the water.