Underground at Wind Cave

We knew it was time to leave Mary Jo's, but we could have stayed. Three nights had been just enough — long enough to have a routine, short enough that the trip still had places to go. The kids hadn't swum in the pool that morning; they'd swum every night, which meant we left the pool as the small ritual it had been all week.

Our drive south on SD-79 took us past more bison alongside the road — a surprise, since we'd thought we'd spent our wildlife currency at Custer State Park — and one coyote that Edrik spotted before any of the rest of us did. Wyoming was waiting again. But first: a stop we hadn't planned.

Wind Cave wasn't on the original itinerary. We'd noticed it on a map the night before and decided to swing through the visitor center to see what the situation was. We arrived a little after noon. The next cave tour was at 1:30. With a long drive to Cheyenne ahead of us, we had a real decision to make: take the tour and arrive at the hotel late, or keep moving and skip what might be the trip's last underground experience. We took the tour. We're glad we did.

While we waited, we explored the visitor center and took a short walk on a nearby trail. I came out of the visitor center with a few facts I hadn't expected. Wind Cave is one of the longest cave systems in the world — surveyors have mapped roughly 165 miles of passages so far, and based on barometric measurements (the cave breathes, literally, with the pressure difference between inside and outside), they estimate that's only 5 to 10 percent of the cave's actual extent. The other ninety-plus percent is still down there, unmapped. And in the deep, unmapped reaches, a team of NASA-funded astrobiologists has been studying microbial life as a window into what life might look like on Jupiter's moon Europa and Saturn's moon Enceladus. The cave isn't just a cave. It's a working analog for the search for life elsewhere.

The tour itself was something. The cave is famous for its boxwork — thin calcite fins that grow in honeycomb patterns on the ceilings, the densest concentrations of which are found here. (Wind Cave became the United States' first cave-as-national-park, established by Theodore Roosevelt in 1903, in part because of those formations.) The temperature underground sits at a steady 53°F year-round, which is a relief after a hot prairie morning above. The kids stayed engaged the whole way. The world above stopped existing for a while; what mattered, for ninety minutes, was where the next chamber opened and what the guide was about to say.

From Wind Cave we picked up a quick gas-and-snacks stop at Coffee Cup #9 in Hot Springs and then settled in for the long drive west: Lusk, then Torrington (where Edrik and I grabbed McDonald's; the girls had food in the car), and on across the Wyoming open country toward Cheyenne. Sierra used the drive to chip away at schoolwork. Edrik played games on the Switch. The hours moved.

I'd booked Cheyenne Little America the night before. I'd considered pushing further south to Fort Collins or Loveland for the night, but the rooms there had been expensive — there were events going on in town — and Cheyenne split the drive nicely. The hotel turned out to be a good call. I'd stop there again.

Edrik and I had eaten on the road; Jacqui and Sierra picked up food from the hotel restaurant once we'd settled in. While they ate, we noticed the lobby and conference-hallway areas had chess boards set up. Jacqui and Sierra played for a bit. It was the kind of evening that closes a long-drive day quietly.

There was, however, one note. Sierra was the only one of us who showered that night. She came out and reported that her water had been cold. The rest of us assumed she just hadn't figured out the controls. We were wrong. We didn't realize we were wrong until the morning.

Tomorrow: a cold shower, a hotel comp, and a long drive south to Rocky Mountain National Park before the redeye home.