If memory serves, it was 2001 when we had a CruiseMates Group Cruise on Celebrity Summit.
We determined the layout of the aft deck on the ship would be excellent, so we set out, and got special permission from the cruise line to try and set a world record for "most kites flown simultaneously from a cruise ship".
The record was not acknowledged as apparently it wasn't a category.
But, we did manage to get 13 kites up at once (which was quite the site), with about twice that many trying to fly them. The lines would get caught so they would come down.
We had to dance through a lot of hoops to get permission, including to strong enough fishing line for the kites that they wouldn't snap, and the ship's environment officer had to be with us.
These days the cruise lines are even more mindful of environmental concerns.
Since then I've seen one person on a ship attempt to fly a kite, and they were stopped within moments.