517. You observe a V-shaped ripple with the point of the V pointing upstream in a river. What may this indicate?

A V-shaped ripple pointing upstream typically indicates a towed-under buoy. This pattern results from the current forcing water to flow around the submerged buoy, creating the characteristic V-shape with the point directed upstream. While submerged objects can create surface disturbances, only a towed-under buoy consistently produces this specific pattern; wrecks and rocks that are not dangerous to navigation are generally too deep to cause such a visible ripple.