When we were on our boat in Antarctica, the bartender (having learned that we were fond of "business juice") suggested that on our next excursion we should look for "black ice" floating in the sea. She suggested that we pull it out of the water and bring it back to her at the bar.
So, we did just that.
So-called "black ice" is the ice that is at the very bottom of a glacier. It was snow that fell on the glacier ten thousand years ago (or so), and then, over time, became compressed by the weight of ten thousand years' worth of additional snowfall. The glacier eventually moved toward the sea, where, at some point, it would break off and fall into the sea.
The result is that the ice was very, very dense. It was crystal clear and pure as 10,000-year-old snow (which is because, um, it's made of 10,000-year-old snow). But in the water, it looks like it's jet-black. Hence the name "black ice."
We brought the ice back to the ship, and turned it over to the bartender. For the next day or two, she chiseled chunks of that ice into a rocks glass for us, and then poured our customary bourbon over it.
Here's the amazing part of it (and I hate the word "amazing" so if I say it's "amazing," you know this is a big deal)...
There were small (very small) pockets of air in that ice. Air that had been trapped in ice for more than 10,000 years. And as our brown liquor melted that ice, and while we sipped it, occasionally the ice would melt and a tiny pocket of prehistoric air would pop. And we'd inhale as we sipped, drinking 12 year old whiskey, and breathing 10,000 year old air.
Like I said...