Richard Chamberlain was 25 in The Secret Of The Purple Reef when he played the character 'Dean Christopher'.
That was over 63 years ago in 1960.
This was his first recorded movie acting credit (although may not technically be his first actual acting role).
Today he is 90, and has starred in 57 movies in total, 55 of those since The Secret Of The Purple Reef was released.
In The Secret Of The Purple Reef, I think Richard Chamberlain looks: