Blake Lively filmed The Shallows stunt scenes while pregnant

Blake Lively filmed many "stunt-heavy" scenes for The Shallows while carrying her second child.

The 28-year-old actress portrays a surfer fighting for her life after being attacked by a great white shark in the waters off a remote paradise in the new horror-thriller, but being pregnant on set did not stop her from taking on some serious action-sequences.

"They didn't hire a stunt double till the last two weeks of shooting," the star tells ETOnline.com. "Every single day there wasn't a single scene that wasn't stunt-heavy."

Filming for The Shallows began in November (15) and Blake was pictured shooting additional scenes for the movie on 12 April (16), just two days before her second pregnancy was announced.

And the courageous star explains filming the action-sequences were no picnic, even though the later scenes she shot while carrying her baby were not as physically intense as those captured earlier in the production schedule.

"Doing the underwater sequences, I'm in 4.5-foot waves," she shares. "Whether I was in the tank or when I was in the ocean, I was about 300 yards away from shore. They would drop me off on this rock that was three feet by three feet."

Blake explains the rock was a pivotal part of the movie, setting the scene for the thrilling story line, because the tiny boulder 'island' was the only thing separating her character from the great white shark hunting her.

"You're in the wild. You are in the land of big, incredible, majestic wild creatures," she describes. "And if you're wearing a wet suit, you're dressed as a seal."

The Shallows reaches theaters on 29 June (16).