Gullfoss Photography Guide
Gullfoss (which means "Golden Falls") is a waterfall located in the canyon of the Hvítá river in southwest Iceland. It flows down into a wide curved three-step "staircase" and then abruptly plunges in two stages (11 and 21 meters) into a crevice 32 meters deep. The crevice, about 20 meters wide and 2.5 kilometers in length, extends perpendicular to the flow of the river. The average amount of water running down the waterfall is 140 cubic meters per second in the summer and 80 cubic meters per second in the winter, which makes it the biggest European waterfall by volume. The highest flood measured was 2,000 cubic meters per second (more at Wikipedia).
When to come
Gullfoss is impressive yearlong and it's also open permanently. In Winter though, some viewpoints might be inaccessible and in general it's necessary to be very careful as it can be very icy and slippery. As usual with waterfalls, the best time to photograph is around sunrise or sunset, but during cloudy days anytime works well. Since the waterfall creates a lot of water mist, you can try to include rainbow, which can be present pretty much from any angle on a sunny day, just depending on time of day (and time of year).
Where to go
From the parking at the Visitors Center walk about 200 meters to a fork.
Either go left and continue for few more hundreds meters to reach the top viewpoint which overlooks the whole waterfall. It offers also nice views down to the canyon.
If you continue down from the fork, you reach the lower level after several steps. There's a very nice frontal view of the waterfall right there. But you can also continue for few hundreds meters along the river to get closer to the waterfall. Composition of the waterfall in the direction down to the canyon looks pretty good from here. You can also try to go even closer to the first Gullfoss stage, but it's harder to find an interesting composition -- and, you and your equipment will also get really wet here, which makes composing great photographs somewhat harder... ;-)
What to bring
Certainly a tripod is very useful for waterfalls photography. Typical shots here require wideangle to moderate telephoto lens. Since there's a lot of water spray, you'll probably need to clean water from your lens often, which requires a cleaning cloth. A water resistant camera and lens could be useful as well.