banozac
I think it's cute that thing humans do when they see a boat pass and the people on the boat wave at them and they wave back. For absolutely no reason. They don't know each other they're not trying to communicate anything other than "LOOK! I am on a boat!!! Hello!!!!" "I see you!!!! On the boat!!!! Hello!!!!!!!!!!!!" in a genuine moment of wholesome human connection and excitement.
I'm a school bus driver and we always wave to each other - for no particularly good reason, just like boat occupants. I tell my kids that it's actually required by law and you can be fired for not waving to other drivers. Hell, for all I know that's actually true.
The public bus drivers in my city do this too :)