Day 7: Tennant Creek to Katherine
It was a bracing 43 degrees when we rolled out of Alice Springs early yesterday. This morning, in Tennant Creek, it's a balmy 72. We're definitely in the tropics.

It's a straight shot up the Stuart Highway today, 400 miles of what should be the easiest traveling we've done so far; our first full day with no dirt roads. There's more traffic today, including a lot more road trains. Imagine an American big-rig with another two trailers tacked on the rear. That's a road train. These supersized semis are about 175 feet long nose to tail, with 16 axles and 62 tires all up, and weigh 120 tons fully laden. The prime movers are usually top-shelf American stuff -- Australian-assembled Kenworths and Macks rule -- with 500-600-horsepower diesels under the hood. The truckies have these babies running at 60 mph whenever they can, which means overtaking one requires patience and planning.

The Stuart Highway looks like we're back in civilization; that the real adventure is behind us. But it's only a mirage: This country is still too vast and too empty to be tamed. As we pass by Daly Waters, famous for its pub, built in 1893 and one of the oldest buildings in the Northern Territory, I radio that the Outback's trip computer is showing we have 125 miles worth of gas in the tank, and that the next gas station is 100 miles up the road.

I can tell the math hasn't quite computed with my American colleagues, as they're happy to push on. But a half an hour up the road, as the fuel needles sink toward E, there are one or two calls back on the radio: "Er, how far until we can gas up again?" In America, you pass gas stations every 20 miles or so on the Interstates; in the Outback you have to plan your journey around gas stops. Forget EVs; you can get range anxiety here in a car that runs on regular unleaded.

We take a 20-mile detour out to Katherine Gorge, a spectacular chain of 13 waterholes carved in deep into the sandstone rock by the Katherine River. The river is a raging torrent during the tropical wet season (November through March), but we have to walk over rocks between our boat rides on the two closest waterholes. Katherine Gorge is sacred to the Jarwon aboriginals, who call the place Nitmiluk. As we drift noiselessly on the tranquil water between the towering rock walls, it feels like we're in a cathedral.