There are at least four isolated populations of the Berg Adder, largely at high altitudes except for the Western Cape where they occur at sea level. This snake averages 30 – 40 cm, reaching 60 cm.

It is fond of basking, especially on mountain paths and rocky ledges. The Berg Adder is a bad-tempered snake that hisses loudly and strikes easily. Its venom differs from most adders in that it is mainly neurotoxic with a specific action on the optic and facial nerves, causing drooping eyelids, double vision, dizziness and temporary loss of taste and smell. Breathing may also be affected in severe bites and bites can be very serious. There is no antivenom for the bite of this snake and victims may have to be artificially ventilated. Some of the symptoms may prevail for several weeks after a bite.