This tall falls is famous for being the waterfall you can walk behind.
This feature gives Seljalandsfoss a great photography advantage. Viewing a waterfall from 360 degrees gives you infinite composition possibilities.
From the road it can look uninviting, but being up close or behind the falls is never boring. During the Winter, the owners restrict access behind the falls due to danger from falling icicles etc.
Seljalandsfoss never sees the sun in the Mid-Winter months. The constant spray and freezing temperatures can make the surrounding area look like a crystal palace. This can also make the area extremely dangerous as the path behind the falls becomes a skating rink. Recently, they have been discouraging access behind the falls after weekly accidents. Winter nights feature 2 spotlights which light the falls. This makes it a poor choice for night or aurora photography.
Although you might have been hoping for a big colourful evening sky, the waterfall works well in rainy conditions. Successful photography is a matter of protecting your camera, lens and self from the spray. A clear plastic bag works well if you are able to compose and focus through the plastic. Then lift the plastic off the lens to take the shot. Eventually your lens will become wet. Take paper towel to soak surplus water and a dry cloth to polish. Start with filters on and work to filters off. Have an assistant help to protect and dry your lens.
Experiment with S (Tv) mode. This waterfall looks good with around 1/20 sec exposure. This sort of speed is good for mono-pod. Most photographers use a tripod, but behind the falls it can be better to have a more fluid system.
There can be good light in the evenings. In the Summer, the sun sets in the North Western sky, it is possible to capture incredible sunsets from behind the falls.