Tilikum, the famous Sea World orca who has famously killed three trainers and who has suffered in captivity since he was captured in the wild at the age of two, is dying. Undoubtedly sad to see such a beautiful animal leave the earth, but it likely feels like sweet salvation for him: the only way to escape his concrete prison.
"...when Tilikum dies he will leave us with something extremely precious, something to redeem his impoverished life in captivity: a desire to give greater moral consideration to other species on our planet, and to re-think the casual ease with which we seek to use nature and all things wild for human purposes. We desperately needed that. For me, that will be Tilikum’s truest and most meaningful legacy."
Outside magazine also has an excellent article that tells more of the story, including how orcas came to be in captivity in the first place. http://www.outsideonline.com/1924946/killer-pool