You don't need a decade on the oars to read water. You need ten minutes and the willingness to look before you leap. Here's the short version.

The V

Smooth water pointing downstream is a tongue — that's the safe line. A V pointing upstream is a rock. Aim for the first, avoid the second.

The hole

A hole is water recirculating on itself, and it's the one feature that doesn't let go. Punch it straight, or go around. Never sideways.

The eddy

Calm water behind a rock is your rest stop. Every scout, every rescue, every lunch happens in an eddy. Learn to catch one and the river opens up.