Zac Efron has opened up about one of the scariest moments of his life. The Baywatch star has revealed what happened when he and his younger brother Dylan encountered a grizzly bear while hiking in Montana to climb the Continental Divide.

Efron recently told People that while he and his brother were out in the Glacier National Park for a Columbia Sportswear ad campaign, the sudden appearance of a grizzly bear made them stop in their tracks.

They also went into silent mode so as to make sure the bear did not feel provoked, but the tactics did not help the brothers.

"Out of nowhere, [we were like] 'Okay, that's a bear. Everybody stop.' And we all stood still," Efron told the celebrity news website.

"Somebody silently whispered, 'But it's charging at us.' It took like two big canters at us."

Despite their efforts to not provoke the bear, the animal rushed at them but then retreated and "disappeared behind some trees".

"It was the scariest part of the trip!" he said.

"But it was cool to see a bear that close. It was maybe 15 or 20 feet away. It was charging at us!"

Efron, who along with his brother Dylan are "gear testers" for Columbia Sportswear, also talked about what he still needs to accomplish in his lifetime.

"I'm about to turn 30, so I'm thinking about how much of the world is left to see, how much there is to do and how much is out there," Efron said. "Luckily this is kind of an excuse for me to get outside even more and follow my dreams and see the rest of the world."

Efron turns 30 years old on 18 October.