Annalisa Alvarado listens to PRI's The World on Capital Public Radio in Sacramento, California. A few years back, she travelled to Antarctica and chanced upon one of the southernmost post offices in the world at Port Lockroy. 

"I was on a cruise with about a hundred other tourists. We were able to buy postcards and actually get a stamp in our passports. Outside of Port Lockroy, there's a Gentoo penguin colony, and the penguins were very curious, especially the younger penguins that are molting.

"They'll come right  up and peck you because they think you might be a larger penguin, or maybe you have some food. So they're just very cute, but they're really smelly.  

"We also took all kinds of pictures of all these different shapes and sizes of icebergs, capturing the way the light refracted off the ice and the different shades of blues.

"You had to take pictures of them, because you knew that each iceberg, as it went by, almost had a soul because you knew it was melting, going into the sea, drifting farther out into the warmer ocean."