Zac Efron will soon be sailing the high seas with Captain Jack Sparrow

– and be bringing home heaps of booty!

Disney has tapped the hunky High School Musical star to join Johnny Depp aboard the Black Pearl in the fourth installment of the Pirates of the Caribbean series – and they’re paying him $10 million for his role, say sources. That’s nearly twice as much as what he was paid for High School Musical 3!

Disney execs first approached Zac – who turned 21 this month – a year ago when Johnny sniffed at the idea of doing "a Pirates of the Caribbean 4," revealed an insider.

"Zac was extremely interested. But in the end, Disney realized that they couldn’t make the fourth ‘Pirates’ movie without Johnny," said the piratical insider. "So they had to offer him a small fortune to do it."

Depp will reportedly take home a whopping $55 million to reprise the role of Cap’n Jack.

But Disney still wanted to groom a successor to Johnny – so they went back to Zac.

Not only will the deal make Zac Johnny’s heir apparent in the Pirates films – it’s a guarantee he’ll make an appearance as basketball hero Troy Bolton in High School Musical 4 – something he hadn’t been gung-ho about doing.

For all the details pick up the latest ENQUIRER.