McAdams, who narrates the Discovery Channel film, explained how she became involved with the project at a special screening on Wednesday. After receiving a rough cut of the documentary from its filmmaker, Adams told PEOPLE, "I was shocked by it and very emotional and surprised about how little I knew about what's going on in our oceans. You don't hear it, but it's a whole cacophony down there."
Compelled by the footage, the actress decided to lend her voice to the project, which was created in partnership with Natural Resources Defense Council (NRDC), Imaginary Forces, and International Fund for Animal Welfare.
In the film, Adams explains the devastating impact that commercial shipping and other manmade endeavors have on oceanic sound waves. "The idea that a baby whale couldn't find its mom because they communicate through sound is so sad," said McAdams, giving just one of many examples of how industrial noise disrupts life under the sea. "And not only whales, but a lot of marine life – even shrimp – depend on their hearing," she added.
Growing up, McAdams lived near a lot of lakes and recalled that her local port was always polluted. "I remember just sitting on the beach because we could never go in the water," she said. "There was always a red flag up." It wasn't until she traveled to Australia at 21 and visited the Great Barrier Reef that she fell in love with the ocean. "I discovered this aquatic world down there that I had been missing out on," said McAdams, admitting "you can't get me out of the water now." Besides scuba diving and sailing, McAdams couldn't forget the beaches she visited there like White Haven Beach "which had the whitest sand I'd ever seen."
Keeping water clean and protecting marine life quickly became one of her priorities. "I want my kids to be able to go down to the little pond and not have to worry about what's in there," said McAdams. She wants to pass on her love for the ocean's creatures to her kids, but "we need to have these species around us forever or for as long as we can. This noise pollution is pushing a lot of them to the brink."
McAdams hopes this film will encourage others as it did her by presenting "tangible solutions and win-win situations." Making ships quieter would use less fuel, which would cut their bottom line and help the atmosphere with less pollution from gas and fuels. Even the Navy has begun tracking where marine life is so they can test their sonar in other places. Rachel envisions that we can solve this by "everybody being a little more mindful."
Could we find her out sailing the waters now? "I don't remember how," said McAdams who became certified in sailing for Wedding Crashers. "That was over 10 years ago now and I enjoyed it at the time, but it's a little intimidating now." She adds, "It is sort of scary that I could take a sailboat out though, so look out!"
Sonic Sea premieres on the Discovery Channel on Thursday, May 19th at 9 PM ET/PT. To learn more visit sonicsea.org.