The official cause of death was pneumonia, which was likely brought on by a combination of factors:
* Compromised Immune System: Keiko had a history of health problems, including parasites and bacterial infections, likely due to his years in captivity and the stress of living in a controlled environment.
* Exposure to Cold Water: While he lived in a natural bay in Iceland in his later years, Keiko still experienced cold water temperatures, which could have weakened his immune system.
* Underlying Conditions: While pneumonia was the immediate cause of death, underlying health issues may have contributed to his weakened state and vulnerability.
It's important to note that Keiko's death sparked a debate about the ethics of keeping orcas in captivity. While his story brought awareness to the plight of captive orcas, the decision to return him to the wild was complex and ultimately unsuccessful.