The ones we were considering are the blue flags. They will mostly line the bank above the higher water line.
As far as "in" the water goes. I'm not sure I'll get anything to grow. (for the previously stated issues.)

9 yr old pond, 1 ac, 15' deep.
RES, YP, GS, FHM (no longer), HBG (going away), SMB, and HSB (only one seen in 5 yrs) Restocked HSB (2020) Have seen one of these.
I think that's about all I should put in my little pond.
Otter attack in 2023