This is a subglacial volcano, that was built up here probably during the last glacial stage of the ice age, about 100 thousand years ago. The highway route 574 between the villages of Ólafsvík and Rif passes right at the foot of Enni mountain, and here in the roadcut you see excellent sections through the rocks. At the base, near sea level, the Tertiary basalt formation occurs. Note the bright red beds of baked soil and ash between the Tertiary lava flows. At and just above the road level, note alternating layers of brown basaltic tuffs and layers of black and angular pillow lava. These are formed during the subglacial eruption stage of the Enni volcano. If you hike to the top of this mountain, you will find a depression in the top, marking the crater in the 400 meter high summit. To get here, turn off route 574 highway between Rif in the west and Ólafsvík in the east. Drive to the southwest on the gravel road to the abandoned farm of Foss. Now you are near a small river and there is a waterfall up ahead, called Kerlingarfoss. Her in the gorge you will see Tertiary basalts at base, overlain by about 10 meters of conglomerate and sandstone from the early part of the ice age. Above this are pillow lavas and breccias that form the base of the Enni subglacial volcano. Hile near the edbe of the plateau to the east. After a while you come to the place marked “dike” on the map. This is a 2 meters thick basalt dike that has been eroded out of the volcanics. Continue uphill until you get to the crest or change in slope. You have now reached the part of the volcano that was mainly erupted above the level of the glacier. The GPS track takes you to the top of the mountain, with great views in all directions. Immediately to the east you are looking into the main crater of the volcano. The descent will take you initially to the south down a vegetated slope. Then the track gradually turns to east and now you are on an ancient trail that leads to the village of Ólafsvík. On the way down you will cross a narrow gully and then a footbridge. After a while this will lead you to the village of Ólafsvík. As an alternative, you can reverse your climb, and start the hike in Ólafsvík.