Prienai-Birštonas loop is home to the Žvėrinčius forest. The area of about 700 ha is mostly covered by dry pine forests. Žvėrinčius forest has preserved its old name, reminiscent of royal hunts. The descriptions of the impressive hunts were documented by a poet M. K. Sarbajevijus (1595-1640) in his ode "Miško Žaidimai". The work also mentions the Forest of Žvėrinčius. The almost closed loops of Nemunas created favorable conditions for hunting. In the Žvėrinčius forest grows a rare peculiar type of pine–the collar pine. The trunk of the pine bark forms peculiar ridges resembling canopies around the trunk of the tree, the tree looks like it is adorned with collars. "Collars" are formed on pines aged 40-60 years. The environment of the pedestrian-cyclist trail is diversified by sculptures of wood carvers from Prienai and Birštonas, respite places and sports grounds for the convenience of travelers. "