From WENN.com

Berg, who filmed the action blockbuster in Hawaii, cast Rihanna in her movie debut as a naval officer, but was so concerned for her safety, he went to extra lengths while shooting in the water.

He tells movie website Omelete, ""My biggest challenge was making sure Rihanna never got eaten by a shark. My fear was that I would be the director that allowed Rihanna to be eaten by a shark. So I was very careful - when she was in the water I had men around her and they were (to make a gesture) if they saw one.""