The flow of water
Go to your local dealer and invest some small money into ND filter. 2x, 3x and 4x ND filter are best. I took them for my wide angel lens and was lucky enough to see that the filter size matches 3 other lenses as well :). If you are smart you will take larger diameter filters and use a step-down adapter ring :) Just a tip. Now stack them together and dial down your aperture to, lets say 16 or even 22. Mount your cam on a sturdy tripod and the next river is your landscape model. Best results are with very long exposure times. 15 to 30 seconds in my case. And do not forget to dial down your ISO to the lowest value ! And now have fun
Olympus E-M5, M.Zuiko 12 mm, 3 ND Filters stacked together, sturdy tripod, 2 second anti shock