Haleakala National Park will celebrate World Ranger Day today with a free screening of the documentary "The Thin Green Line."

The 2007 film by Australian park ranger Sean Willmore looks at rangers at work across the globe. It will be shown at 7 p.m. in the poolside meeting room at the Mayor Hannibal Tavares Community Center in Pukalani.

World Ranger Day was created by the International Ranger Federation, a consortium of national and state ranger associations. The observance pays tribute to rangers who protect the world's natural and cultural heritage, and honors rangers injured or killed in the line of duty.