With filming currently taking place for their next project in Hawaii, it seems that the comradeship of actors Zac Efron and Adam Devine has officially graduated to a full-blown bromance.

Not content with spending all day together on the set of Mike And Dave Need Wedding Dates, Zac, 27, and the 31-year-old Pitch Perfect star even opted to hang-out during their down-time on the tropical island.

This week, the pair decided that swimming with tiger sharks – the species which is responsible for more fatal attacks than any other – would be right up their street.

Zac, who reckons the tiger shark is his 'spirit animal', posted on Twitter a three-and-a-half minute long video clip of their underwater experiences, something which then generated more than 2,000 retweets.

The High School Musical star said he hoped his efforts would help raise awareness of the shark's endangered plight.

Still, elements of the clip have proved controversial – namely Mr Efron's decision to grab hold of one of the animals (the incident occurs at around the 2:18 mark).

While speaking to TMZ, one expert, Jeff Kurr, even warned that the dive itself was reckless. He explained that tiger sharks are extremely dangerous and unpredictable – and that grabbing a fin is an aggressive invite to a deadly attack.

Earlier in the week, Zac turned heads in a blue unitard costume while on set.