Which hazards should paddlers avoid on rivers?

Paddlers should prioritize safety by avoiding hazards that pose significant risks on rivers. Low-head dams are particularly dangerous because they create a ledge effect, pulling water back on itself, which can trap and drown paddlers who get too close. Strainers, which are obstacles like fallen trees that allow water to flow through but can trap boats and their occupants, can create a serious risk of entrapment. Rapids, while sometimes exciting, can also present challenging currents and obstacles that inexperienced paddlers may find difficult to navigate safely.

By recognizing and avoiding these specific hazards, paddlers can better protect themselves and enhance their overall experience on the water. The other options may describe conditions or features that, while they can present challenges, do not generally pose the same level of immediate danger as low-head dams, strainers, and rapids do.