It's one of those mysteries that have engaged people for hundreds of years. The usual suspects are always trotted out, but in the end there is no solution.Speculation is futile. we'll never know. Accident or suicide seems the most plausible. Antinöus was 20. That was remarkably old for someone in his profession. Hadrian had only just been so ill that he was expected to die. The life of Antinöus after the death of Hadrian could not have seemed very attractive to the boy. Who knows? Perhaps no one ever did.