When I was a child we used to joke that Greenland was icy while Iceland was green, and I think when I went to visit Seljalandsfoss that green epitomy was at its height. It was a rainy, misty, miserably wet day, and it was my first day driving around Iceland -- I wondered what I'd gotten myself into because it wasn't really that much fun to drive in, even if it was beautiful (what little you could see).
Seljalandsfoss comes up out of the mist after driving along a flat boring plain for hours. It is a 60m high falls tumbling off a cliff rising from the flats, and you can see it from the ring road, along with the other cars and buses at the parking lot right below it. I stopped because it was the first waterfall I'd seen that day (I would go on to see around 15 more), not really realizing how magical it was. It's one of the most famous waterfalls in all of Iceland and adorns many postcards and calendars. A really great sunny day photo of the waterfall can be found here. The waterfall is located between Selfoss and Skogafoss just off the Route 1 Ring Road on the track going to Thorsmork.
When I was a child I watched Robin Hood bathing in a waterfall (I think that was the gossiped about naked Kevin Costner scene!) and thought how cool it was that there were waterfalls that you could go behind. I finally got to experience that magic at Seljalandsfoss. It was the fairy tale, dream-like secret path that could lead to hidden caves and mysteries... except it was just a path... although it was magical.
Wet-weather clothes were something I'd bought at the last minute before leaving for Iceland, not really having packed wisely when I'd left home several weeks before. Into dry pants and jacket I scrambled for the rain, but I would have needed them for the waterfall anyway. Going behind a waterfall is wet business!
Here are some videos where I tried to catch the magic (or at least try and catch the wet before it splashed and fogged up the camera!).