Seljalandsfoss was our very first stop after arriving in Iceland. We drove straight from Keflavik International Airport to Vik, the first town we were staying in. On our way to Vik we stopped at Seljalandsfoss and Skogafoss. Both were insanely packed with tourists but that was to be expected!
Seljalandsfoss is very easy to get to and you can see the water tumbling over the edge of the cliff from miles away (even on a rainy day). Fortunately for us this was only one of two rainy days we had in Iceland (really, REALLY lucky for being there during the Autumn).
To get to the waterfall we simply took a left off of the Ring Road (main highway in Iceland, Route 1), drove up, got out of the car, walked a few steps and we were there. You can also hike back behind the waterfall. If you keep hiking further down the path (to the left of the waterfall if you're looking straight at it) you can hike up and around to above the falls and find another hidden waterfall in a crack/cave like structure in the rocks. We started to do this then it but it started hailing on us. Yes, hailing. The weather in Iceland can be really, really insane. We were tired and cold so we ran back to the car (Michael stopped to get us a hot coffee at the gift shop at the base of the falls).
(If it looks like there aren't as many tourists in some of the pictures it's because I photoshopped them out! Michael and I pegged the amount of tourists at this waterfall around 75-100)