It will stay submerged.

Pluses and minuses:

+ Great cover for invertebrates and for fry and fingerling fish to hide

+ Produces beaucoup oxygen
+ It competes with filamentous algae and other invasive macrophytes and can preclude any problems with them

- Decomposes underneath and adds to the muck layer
- Too much cover for forage is not necessarily good for predator fish
- It can get seriously out of hand but not always

If pigs could fly bacon would be harder to come by and there would be a lot of damaged trees.