Matt Damon, who made a convincing action hero in the “Bourne” franchise, now wants to play a superhero. Word is our Hollywood homeboy has signed on to star as Aquaman in the big screen version of the DC comic book “Justice League.” To be directed by Zack Snyder, the movie will be a sequel of sorts to “Batman vs. Superman,” which stars Damon’s buddy Ben Affleck as Batman. (Affleck will also be in “Justice League,” as will Henry Cavill and Gal Gadot, who play Superman and Wonder Woman, respectively, in “Batman vs. Superman.”) Not familiar with Aquaman? He’s the telepathic ruler of all the oceans and possesses incredible strength and speed — of course — and the ability to command sea life. Thanks to his unusual physiology, Aquaman also can survive on land and in the deepest ocean. At 43, Damon might be a bit old for the role, but he’s certainly no stranger to H2O. Damon is cofounder of Water.org, a nonprofit that helps developing countries that do not have access to safe drinking water and sanitation.