Can mavic mini fly over water?

Yes. There are many YouTube videos of MM flying over water. Just don’t run low on power and have a forced landing.

Hello and good day. I am sorry for the trouble and thank you for reaching out. It is not recommended to fly the aircraft close to the water. When flying above the water, the vision system of the said drone  will turn off automatically, if the vision system is affected an accident might happen. Thank you and have a safe flight always.