All swim areas should have swim buoys and swim lines . . . and for good reason . . . it makes it very apparent that that area is a swim area and for boaters to stay clear. Without these buoys and swim lines there is no way for boaters to know what is a swim area and what isn't.
Under no circustances should anglers troll inside swim buoys/lines.
About the water balloon thing . . . of course you are joking