Kaihunharju is a sharp-featured esker ridge surrounded by waters. It was deposited in a subglacial tunnel stream and crack between ice masses around 11,400-11,300 years ago. The Kaihunharju area is situated in a built-up area and is home to the marked network of paths called the Kaihu trail. There are connections to the Urpola nature centre (Saimaa Geopark visitor centre) and also to the Pursiala pothole. The Kaihu trail is signposted by Saimaa Geopark signs.