We just got back from WDW Monday and had done the parasailing for the 1st time. We booked a tandem and it was an amazing view.
We treated it as we would the carriage rides and such and we did tip. There were a driver and an asst so I just tipped $20. There was 1 other couple in the boat and I noticed they didn't tip, even though they had their picture taken by the asst and they both raved about the experience.
To each his own I guess.