The 16-sq-km John Forrest National Park, 8km west of Mundaring, was WA's first national park (1900). Protected groves of jarrah and marri are scattered about granite outcrops, with waterfalls and a river pool…but the big-ticket attraction here is the amazing 340m brick-lined Swan View Tunnel, designed by legendary engineer CY O'Connor. The tunnel saw train action from 1894 to 1966.
Note that some park gates close at 4pm.