User blog comment:TombRaiser/Dragonborn: Hidden Landmarks/@comment-173.63.167.103-20121215230654

In order of difficulty from hardest to easiest they are:

Mortrag Peak (Arvak is necessary, don't go too fast you you will fly off the mountain and die, also, do not get off of Arvak on top of the mountain or you may fall through the mountain)

Frykte Peak (Arvak is necessary at the top, or you will fall through the mountai dou to a glitch)

Mount Moersing (Arvak is unnecessary)

Hvitkald Peak (Just go behind the lodge and start climbing the mountains that start just past the Dwarven Ruins, follow them back to the lodge)