Seems like most cruise lines offer the option of pre-paying gratuities these days. It’s not mandatory. We bought about 400 shares in March 2020 with a cost basis of $10.15 per share, without even knowing about the onboard credit. My annualized return is 13.38%. Would have been more if I had know about the shareholder benefit on our last 3 cruises, lol! But fortunately learned before our 15 day Panama Canal cruise, so $250 OBC for the win!