Blue Mountains (NSW): Many bushwalks in the Blue Mountains National Park offer awesome views of valleys, waterfalls, cliffs, and forest. All are easily reached from Sydney.
Whitsunday Islands (QLD): Most people think of snorkeling and watersports when they come to these subtropical national-park islands clad in dense rainforest and bush, but every resort island we recommend has hiking trails. Some are flat, some are hilly. Wallabies and butterflies are common sights. South Molle has the best network of trails and 360-degree island views from its peak.
Lamington National Park (QLD): Few other national parks in Australia have such a well-marked network of trails (160km/99 miles in all) as this one, just 90 minutes from the Gold Coast. Revel in dense subtropical rainforest, marvel at mossy 2,000-year-old Antarctic beech trees, delight in the prolific wallabies and birds, and soak up the cool mountain air.
Larapinta Trail (The Red Centre, NT): You can now start off from Alice Springs and walk the entire 250km (155-mile) semidesert trail that winds through the stark crimson McDonnell Ranges. You don't have to walk the entire length, as plenty of day-length and multiday sections are possible. This one's for the cooler months only (Apr-Oct).
Kakadu National Park (NT): Whether a pleasant wetlands stroll or a tough overnight hike in virgin bushland, you can find it in this World Heritage-listed park. You'll see red cliffs, cycads, waterfalls, lily-filled lagoons hiding man-eating crocodiles, what sometimes looks like Australia's entire bird population, and Aboriginal rock art.
Cape-to-Cape (WA): Rugged sea cliffs, a china-blue sea, eucalyptus forest, white beaches, and coastal heath are what you will find hiking between Cape Naturaliste and Cape Leeuwin, in the southwest corner of Western Australia. In season, you'll see whales and wildflowers.
Freycinet National Park (TAS): The trek to Wine Glass Bay passes pink granite outcrops, with views over an ocean sliced by a crescent of icy sand. It's prehistorically beautiful.
Cradle Mountain & Lake St. Clair National Park (TAS): The 80km (50-mile) Overland Track is the best hike in Australia. The trek, from Lake St. Clair to Cradle Mountain, takes anywhere from 5 to 10 days, depending on your fitness level. Shorter walks, some lasting just half an hour, are also accessible.