The Botnsa river runs from the second-deepest lake in Iceland, Hvalvatn (525 ft.), into the sea at Hvalfjordur. Botnsa river passes through a magnificent canyon, into which spills Iceland's highest waterfall, Glymur, which is around 650 ft. high and popular for wintertime ice climbing. People wonder about the derivation of the place names in this area and one delightful folktale, telling the story of Raudhofdi, explains the origins of some of them.

In short, the story tells of an elf-lady who was so enraged by a man who'd betrayed her confidence that she turned him into a whale. The whale was always known as Raudhofdi and he was the scourge of seafarers in the region. One of Raudhofdi's victims was the son of a local priest. The priest was blind and short-tempered, but nonetheless a wily character. One day, he took his staff and daughter and blundered his way along the land bordering the water. It wasn't long before Raudhofdi came swimming into the fjord and followed the priest all the way up to Hvalvatn Lake. Because the priest was on higher ground, the whale had to battle his way up a waterfall - and his thrashing caused a din that sounded like an earthquake. The Icelandic word for this booming noise is "glymja", said to be the origin of the name of the waterfall. When Raudhofdi finally reached Hvalvatn Lake, his body was so worn out that it exploded. The whale-bones that have been found on this spot are said to prove the truthfulness of this tale!