The song is a metaphorical record about anxiety, and was inspired by Brown's experience with infidelity by a past boyfriend who liked to stalk her in his free time.

Popjustice gave the song a positive review, writing "Immediately brilliant - a reinterpretation rather than a continuation of the 'indie doo wop' schtick she's been working on over the last couple of singles and therefore a lot less stylised and a great deal more accessible.

"[3] Nick Levine of Digital Spy gave the song 5 out of 5, stating "It begins in bright, breezy fashion, all-girl group backing vocals and guitar-strumming that brings to mind Craig McLachlan's 'Mona', before something a bit magical happens - the arrival of a pure pop chorus as huge and all-consuming as a T.rex that's just come off hunger strike.

"[5] Music OMH writes: "'Shark in the Water' could easily be described as a 'summer anthem', all breezy acoustic strums, insanely catchy melodies and a chorus that explodes seemingly from nowhere.

'Baby there's a shark in the water, I caught them barking at the moon' is a wonderfully mixed image, the kind of animal creation a cartoonist would balk at for being too ridiculous.

In the summer of 2010, a Degrassi promo aired in both Canada and the United States, for season 10, and was featured in the mid-season finale, All Falls Down (Part Two).