Now we all know One Piece isn't always happily ever after.
So my question to you is:
What do you think is the saddest moment in OP? and why?
This is a nice compilation of almost every sad moment in one piece till Robins past/CP9 (beautiful video btw)
It's missing the story of Brook and boa & the deaths of Ace, White Beard and Sabo.
One of brook's past: