Scott Eastwood Illegally Dives off Cliff in Australia

Scott Eastwood was up to no good on his day off in Australia ... and he probably didn't even know it.

The actor's in Sydney shooting "Pacific Rim" ... and on his day off Tuesday he decided to hit up Wattamolla Falls at the Royal National Park.

Problem is ... it's illegal to dive from that cliff. If authorities decide to go after him, Scott may have to pay a fine ... which we're guessing won't be a problem.

Oops.