General
Mount Hestfjall í Grímsnesi (322m) is located in the South of the municipality Grímsnes og Grafningur in the district Árnessýsla. There are numerous other mountains in Iceland called Hestfjall (hestur = horse, fjall = mountain).
Its peak is called Hesteyru (= horse ears) and it is almost completely surrounded by the Hestvatn Lake and the Hvítá River.
Legend has it that a huge, horselike monster called Nykur lurks in tunnels under the mountain. It usually keeps quiet and stays in its cave, but when it leaves, the Hvítá River flows into the tunnels and the land dries up. Such incidents are nowadays explained by ice dams which sometimes cause floods in the county Skeiðahreppur during winter.
View
On clear days, the view from the top is spectacular in all directions. It is said that more than 20 churches can be spotted here.
Some of the mountains you can see:
West: Ingólfsfjall, Búrfell
North: Kálfstindar, Efstadalsfjall, Vörðufell
East: Hekla
South-East: Þríhyrningur, Tindfjöll, Eyjafjallajökull, Westman Islands
Map for better orientation
Geology
Mount Hestfjall is a shield volcano, built almost entirely of fluid magma flows. However, it is not completely evolved since apparently a glacier prevented the lava from further spreading.
The steep slope is explained by sea erosion, i.e. a much higher sea level between the end of the ice age and the beginning of the Holocene epoch. Thus, Mount Hestfjall and many other mountains in this area were islands for some time.
Lake Hestvatn at the foot of the mountain covers an area of about 6km^2 and is 60m deep, meaning it reaches 12m below sea level.
