Blackfish
http://www.blackfishmovie.com/
This documentary film discusses about the history of SeaWorld and how killer whales are affected by captivity. The film is rather engaging by using graphic scenes and interviews.
Joe Rogan Experience
This podcast clip has Joe Rogan talk with Kelly Slater about SeaWorld mistreating their killer whales and how a whale should be free from captivity. Using their voices the audience can listen to a discussion. (Note: strong language used)
Aeon Article
https://aeon.co/ideas/stop-boycotting-seaworld-if-you-care-about-marine-conservation
This article takes a deeper look into SeaWorld and how supporting SeaWorld can actually help more animals rather than destroying the environment. Using statistics and logic, there are many reasons to convince why it is important to save SeaWorld.