Amber Heard Gets Cheeky in Nearly NSFW Photo

Amber Heard is feeling free in Bali!

The Justice League actress gave fans a glimpse into her island vacation with a sexy snap of her backside while slinking out of the pool. To turn up the heat, Heard was wearing only a pair of cheeky black bikini bottoms and a sunhat.

“When in Bali…” she captioned the revealing photo.

When in Bali...

A post shared by Amber Heard (@amberheard) on

The 31-year-old is living it up with a friend and judging by her frequent Instagram posts over the last couple of days, the pair is embracing the island lifestyle—dancing, sun-soaking, eating and relaxing.

Heard’s enviable snaps also highlight her super fit bikini body (especially when she’s sans top). The actress began filming Aquaman this summer, a comic-based film in which she plays sea queen Mera. In true superhero fashion, she wears a skin-tight suit throughout the movie, requiring her to put in major work to achieve her strong, fit physique.

Heard committed fully to this challenge, says Gunnar Peterson, one of her trainers for the film. “She wanted to deliver for the character,” he told PEOPLE.

Peterson says Heard trained with him four to five times a week “for a non-stop, no-breaks hour with me, and THEN she went to her fight training, which was rigorous!”

Another day at the office #Aquaman #fighttraining @87elevenaction @jonvalera

A post shared by Amber Heard (@amberheard) on

During their sessions, the pair focused on full-body fitness rather than toning specific areas.

“Everything was athletically based. We trained movements, not muscles,” Peterson says. “Squat presses, sled work and lots of work in a rotational plane against resistance. She is a true athlete.”

He says her commitment to the role and to all the work that came along with it helped her achieve stellar results.

“She could not have been better!” Peterson says. “If I could bottle her drive and conviction I’d sell that as a pre-workout drink!”