Akkaya Travertines Akkaya Travertines, located on the Mudurnu road and 10 kilometers southwest of Bolu, is known as "Bolu's Pamukkale" and has a beauty worth seeing. One of the only natural environments to remain intact in Bolu and the Western Black Sea Region is Akkaya Travertines. The region's water is rich in calcium at a temperature of about 20 degrees. The result of the volatilization of carbon gas in the water flowing from terraced surfaces, lime was released and limestone remains covered were formed. Travertine pools of mineral water, which have a mild taste, are the main attraction at this park. The spring provides visitors an opportunity to swim in its natural rock pool or sip on the refreshing water straight from a fountain.