It sounds like an amusement park. Or a portion of a zoo reserved for marsupials.

But Kangaroo Island, 30 minutes by air from Adelaide in South Australia, is just the opposite. With more than a third of the island protected by natural reserves, this remote, pristine wilderness — seven times the size of Singapore — has immense stretches of unsullied bush land. Birders, animal lovers and nature buffs flock here — to “KI,” as locals call it — to wander the largesse of Flinders Chase National Park, which offers wonders such as penguin colonies, the sea-sculpted Remarkable Rocks and the stalactite-dripping Admirals Arch.

KI’s wild beaches, historic lighthouses and rugged scenery have been accessed in the past by ranger-supervised roads and pathways. But much of the terrain remained inaccessible to visitors until this year. Opened to the public in May, the Kangaroo Island Wilderness Trail, a nearly 38-mile, five-day hike, ushers audacious trekkers on a botanically distinctive immersion into the island’s southwest side.

Footers can expect to walk roughly four to seven hours a day, passing colorful flowers dotting heaths, splendid sugar gum trees, acacias and scores of indigenous plant life. In this timeless setting they’ll likely spot kangaroos, goanna lizards and spiny echidnas. From cliff rims they’ll peer into the Southern Ocean, where sharks lurk and schools of salmon cluster in flowerlike, protective formations.

The trail includes four camping areas, each outfitted with 24 tent platforms: 12 for self-guided walkers (who must reserve a spot in advance) and 12 for tour operators, who also can arrange lodging options off the trail; kangarooisland wildernesstrail.sa.gov.au/home.

Independent trekkers pay about $124 to do the walk; the cost includes the park entry fee, car parking at the Flinders Chase visitor center, and a trail guide and map.

KI is accessible both by air and by ferry; tourkangarooisland.com.au.