USHUAIA, Argentina (AP) - Online photo albums I had prepared for family and friends were not capturing the essence of my travels to the southern reaches of the world. Then a light bulb clicked as I was exploring Google Earth: Why not use that?

Google Earth is a mapping product much more powerful than the typical web-based map service. Applying mathematical algorithms to actual satellite and aerial images, with help from topographical data collected from the space shuttle, the free software lets you explore the world from your computer with remarkable realism.

Much of the magic comes from regular users: You can broadly share your expertise on specific locales by adding comments, embedding photos and distributing them to the world.

I could not wait to contribute my own majestic views of glaciers, forests and the Beagle Channel - shot during an 18-day trip to Antarctica and South America, the third and fourth continents in my ongoing quest to run a marathon on all seven.

Figuring out how to use Google Earth proved challenging, though, and figuring out how to share my collection with friends was even trickier.

I quickly got overwhelmed because the software can do so much, and I could not see where or how to begin. Google Inc.'s online user guide provided so much information that I got impatient with it. Relief finally came once I found step-by-step directions on an online bulletin board.

I began by finding Ushuaia and my hotel on the map, adding what Google calls a "placemark" - which I discovered to be a three-dimensional bookmark that remembers the location, altitude and angle from which you are viewing.

I added several placemarks along the route of the 2007 Fin del Mundo Marathon, a task that proved difficult because nearly half the race was through a national park that appeared primarily as a large green spot on the satellite image.

I had to approximate the route using landmarks such as streams and mountains in the photos. I spent too much time trying to find - without success - the waterfront Kuar restaurant I had passed while running and dined at two nights earlier. (If you can find it, order the seafood crepe.)

Had I brought along a GPS device and "geotagged" my photos with latitude and longitude coordinates, a technique still mostly limited to the tech-savvy and professional photographers, this wouldn't have been an issue.

About 12 miles into the race, I had stopped briefly to take a photo of houses with snow-covered mountains in the background. Initially, I added a simple placemark as if the location were viewed from above - like what you typically see on web-based maps.

But then I sought to match what was on the screen with what I had in my photo.

That meant tilting and rotating the Google Earth view until I was looking north from nearly ground level. The match was not perfect, but quite impressive.

I quickly came to appreciate the power and realism of Google Earth.

I am fairly comfortable with the basics of Google Earth now, and I do enjoy creating the presentations. But it's like the proverbial tree falling in a forest with no one around to hear it: Sharing my Google Earth creation was far more cumbersome than sending a link to an online photo album with an easy-to-find "slideshow" button.

Although many of Google Earth's features are likely second nature to longtime users, they are relatively new to me and people I know. Google says it is working to improve usability, and I look forward to seeing future iterations.