This scenic trail explores One Tree Bridge and the Four Aces and the towering forests in between. The northern part of the loop is steep and descends into the Donnelly Valley.
One Tree Bridge was built in 1904 by felling one immense Karri tree over the Donnelly River. The bridge was in constant use until 1943, surviving several bush fires.

The forest surrounding One Tree Bridge was declared priority area for conservation and recreation in 1974 and contains patches of 400-year-old virgin Karri as well as younger forest regrowth after logging.

There is an underpass to for the bridge which crosses the Donnelly River. The area is very picturesque and there is good fishing and marroning along the river.