The rock on the eastern side of Tysnes is rich in lime. It was used for lime burning for many hundreds of years and provided the farms in the area with an unusual supplementary income until 1900. The lime was shipped to Bergen and used in house-building. There are remains of sveral lime ovens in the area around Flakkavågen. The lime oven at Flakka was restored in 1992 by Tysnes cultural heritage assocation in collaboration with Tysnes Municipality. The oven is situated at Flakkavågen, approx. 2 km south of Onarheim. There is an information board by the main road.