Brúarfoss is also called the blue waterfall and means "bridge over waterfall". The river Brúará flows down over 2-3 meter and ends in a U shape slot. The waterfall is very photogenic because of this shape and the blue color of the water.
Take road 1 up to Mosfellsbær. Turn into road 36 to Þingvellir. From there take road 365 to Laugarvatn and in addition take road 37 in the direction to the Geysir. About 2-3 kilometer after you crossed road 355 you will cross the river Brúará. Here you can also find a small parking. Walking upstream brings you to Hlauptungufoss and Brúarfoss. The trail is a bit muddy at places when it rains but the walk is quite easy. Between Brúarfoss and Hlauptungufoss there is another small waterfall called Miðfoss.
The walk takes approximately 45 minutes and is 3.5-4 kilometer long.