Alternatives to twinning Killarney National Park with a location in the United States were considered.
Earlier this year, government bodies in both Ireland and the US agreed to pair the Kerry park with Glacier National Park in the state of Montana.
A five-year agreement was signed by the National Parks and Wildlife Service, which manages Killarney National Park, and the US National Park Service, which manages Glacier National Park.
Discussions on the partnership had been ongoing during the pandemic.
In August 2020, the NPWS told the US department that Killarney National Park is the ideal candidate on the Irish side, but others are available, depending on their plans.
Glenveagh National Park in Donegal was an alternative named.
The NPWS said there are strong links between Killarney and the US, including the Philadelphia-based McShain family, which had gifted Ross Castle and 8,000 acres of parkland to the state.
After delays compounded by the pandemic, the agreement was signed in March of this year.
As part of the partnership, the parks will exchange knowledge, data, technology and training.
