Mount Esja is an excellent challenge for everyone. Each person can choose their path according to their physical fitness because there are several hiking options on Mount Esja. One should start at Mógilsá and from there the route is very well marked. Mount Esja can be seen from Reykjavík and from that distance it seems to change color constantly, some say to match her mood. The color changing has a more rational explanation though: the colours are reflected by the light on basal salt rocks and palagonite minerals. The mountain is 909 meters above sea level and is believed to be 3 million years old! A hiking trip on Mount Esja is hugely popular among people in Reykjavík.