long nets usually have a pope on either end. it is the way they are retrieved AND it is the way to identify the nets. I've already come up on nets before realizing it because of the distance between the poles. Paying attention I was always able to stop short of the nets. lots of boating hazards, it is not like driving a car.
Real hazards are the river systems series of dams. the older dams have no super structure above them. so coming down river it is easy to actually miss the 5 buoys and go over. If you saw the Bruce Willis movie "Striking Distance" (great flick), you see the chase scene where boats are actually driven over the dams. It can be a scary experience. I've boated on the Mississippi river system for 40+ years. River barges maybe 30 with a power tug are the biggest ships afloat. At night they use to have only one small dirty red kerosene lantern on the front. any I've seen many that had blown out, and were marker less. they just grind you up and keep going, not knowing they impacted.
Boating needs a full time attention, especially at night.
BEAR