"The island of Gaddtarmen (Hauensuoli) off Hango (Hanko) forms a natural harbour on a sailing route in the east-west direction. Sailors have made more than 400 carvings on the rocks while awaiting favourable winds. The oldest drawings date from the 15th and 16th centuries.
Throughout history, Hankoniemi Cape has been an important halting place for seafarers in the Gulf of Finland, being already mentioned in the Early Middle Ages in the so¬called Danish Itinerary of sailing routes in the Baltic. The oldest engraved markings at Hauensuoli date from the 15th century and in the following century it was famed for its sheltered harbour and rock drawings, being mentioned in Olaus Magnus's "Historia de gentibus septentrionalibus" (1555) among other works. The site is mentioned by later historians and travellers from the 17th century onwards. The rock drawing area at Hauensuoli encompasses roughly three hectares on the two islands with over 600 drawings, mostly from the 16th and 17th centuries."