in the shallows of where? Are you living by an estuary or something?
If you can even get a barrel and lob in some duckweed, elodia maybe, and a few reedy sort of things sticking up you'll likely get dragonflies breezing through. They seem to crop up all over the place, even in urban type settings, once they have water and stalks to perch on to look at the water.
I'll be putting in a little pond in the non-sea side of the place here. There's a sporadic leaky tap here, which if it's leaking invites all sort of birds and things down, and you'll see the odd dragonfly ripping past if they see the pool forming. They're really active and good at seeing stuff.
I'm sure I've mentioned where I am before and don't want to anything too specific.
Where I live is tidal, I'm out of the water about 8 out of every 12 hours. So at low tide I'm in the mud, seeing mad things out the window.