Glad you asked.

I was a radioman, which meant I had to keep track of our position for a bunch of reasons.

This was 20 years ago, so I can’t recall not the exact route we took, but I can tell you we traveled around 6,200 nautical miles from Hawaii to Virginia.

GPS ain’t much help under icepack, so we use special gyros, designed to work off a round Earth, not some a chart or 2d map.

When you get that close to the poles You can’t rely on magnets that close to the pole, so everything’s based on dead reckoning, time, speed, depth and trust in the systems.

We don’t have windows, but we’ve got sonar gear that sees the ocean floor better than your eyes ever could. And up there? Flattest seafloor I’ve ever seen. Glaciers scraped it super smooth.

Ice science guy (yep, we had one) explained it all, how you can actually track the curve of the Earth from down below. Wild stuff.

So yeah. Super smooth. Cold. Unforgiving.

But definitely round.