Located in the Kefken region of Kandıra, Pink Rocks deserves to be at the top of Kocaeli travel lists with its interesting geological structure. Although the pink rocks, which have been used as a quarry since ancient times, are soft in water, they harden after being removed. This feature of the rocks enabled them to be cut and transported to Istanbul by sea during the Ottoman Period. The cut pieces were used in the construction of many mosques and Anadolu Hisarı in Istanbul.