The Dandenong Ranges are a group of hills forming the eastern boundary of Melbourne, Australia, about 35 km east of the central city. They can be seen from most parts of Melbourne, and are easily identifiable as a group of three hills with large television towers.
Four chunks of the ranges form the Dandenong Ranges National Park , whose highest peak is TV tower-topped Mount Dandenong itself (633 m). The valley between the hills has the pleasant towns of Olinda, Sassafras and Kallista, and the wineries of the Yarra Valley are just to the north. Although there is a suburb called Dandenong in Melbourne, it is 30km from the mountain of the same name. Make sure you double check!
The Dandedongs can be reached by Belgrave line Metro trains from Melbourne in just over an hour. Outside rush hour, you may need to board a train to Lilydale and change at Ringwood. Two park information centers are near Upper Ferntree Gully station (one on the Railway Rd side, the other 10 min away at the Ferntree Gully picnic grounds), while Puffing Billy (see below) leaves from near Belgrave.
Alternatively, take the train to Croydon on the Lilydale line, and continue by Ventura  bus 688 to Mt Dandenong and Olinda. The service is infrequent, but it's the only way of reaching either on Sundays.
As ever in Australia, a car will come in handy for touring the area, especially on weekends.
US Buslines runs several buses in the area. All are in Metlink Zone 2 and run very infrequently, so check schedules beforehand.
It is possible to catch a train there and go on several walks near the Dandenong train station.
Cycling is possible, but only for intermediate and advanced cyclists.
Running  is also possible.
Unless you're touring by car, you'll need to bring along your own supplies: there's a supermarket and a few basic eateries next to Upper Ferntree Gully station. The National Parl has half a dozen picnic grounds with barbecues, shelters and water.