Bubbles of foam floating on the surface of dark water in the North Esk river in Scotland slowly lap against the river bank while a fast-flowing river rushes past a moss covered cliff in the background

stream fresh water river bank fastflowing froth whitewater flowing river water ripple churn tide moss foam flow foamy turbulent lapping surface pollution spume foaming carbon surge float cold shifting fishing salmon floating bubbles circulate movement swirl cliff whirl drift bubble contrast change fast current twist organic patterns white lap eddy black