Plastic bags, bottles, cans and human faeces are among the items being discarded in Killarney National Park.
Séamus Hassett, who works with the National Parks and Wildlife Service and is based in the national park, says there has been an increase in visitors in recent weeks.
This had led to increase in the amount of discarded litter.
A national campaign – Love This Place, Leave No Trace – has been launched to promote responsible behaviour outdoors to combat the increase in littering.
Leave No Trace Ireland, which has published guidelines to protect the outdoors from littering, says everyone has a responsibility to bring their litter home.
Séamus Hassett says the types of litter in Killarney National Park are widespread and varied.