I wrote about 15 pages in my journal on this subject, but I will spare you most of the details. I´ll just put down the important ones. 
The first day of our trip started off with a visit to the locomotive cemetery. These are steam engines which had been put into service around the 1870s and decommissioned in the 1950s, all this time used to haul minerals from Uyuni and Potosi. They were put on the edge of town in hopes of restoring them – this never happened, so now they are slowly rusting away. There are a few dozen locomotives, actually in pretty good shape except for the rust. It was fun to clamber in and around them – no way you´d have that much run of a place like this back in Canada. Dan really seemed to enjoy it, and I´m glad we found at least one place to visit that was mostly for him.
The rest of the first day we spent visiting Salar Uyuni itself. It is a remnant of an ancient inland sea. The Salar Uyuni segment now floods every year during the rainy season, dissolving some of the top layer of salt, and bringing some more down from the mountains. The lake formed during the rainy season is actually bigger than the salt flat was the previous year, so as the dry season comes and the water evaporates, the salt deposited expands the area of the Salar a little bit each year. The result is that in the oldest parts of the Salar, salt deposits are up to 8 meters deep, while at the edges it´s just a few millimeters. The thicker the layer of salt, the more pronounced the cracks in the surface, forming an endless pattern of irregular octagons. Salt is actually “mined” from the lake, but only for internal Bolivian consumption.
In addition to driving on the salt flat itself, for hours (it has a total area of 12,000 square kilometers), we visited Island de los Pescadores, a little hill in the flat which becomes an island in the wet season, and is home to some truly impressive cacti (up to 12 m in height and 900 years old). At the top of the hill, volcanoes in every direction made a great backdrop for the cracked pale earth in every direction, and the associated mirages.
The second day was a real test for our 4×4 ride. We went up and down sand dunes and rock gullies, through a few different types of desert (rock, hard packed sand, soft flowy sand), and even a transport “highway”, which was just a 4-car-wide packed dirt and gravel road.
It was also a day for wildlife – we saw (and fed bread to) a sly little fox who approached our car; we saw herds of vicunas, which are endangered in Peru but apparently quite alive and well in Bolivia; local long-tailed rabbit (looks very much like a cat); and what I think were chincillas. And, of course, the main highlight – flamingoes. Lots and LOTS of flamingoes. Until that day, I always thought of flamingoes as tender tropical animals – it´s never occurred to me that they could live in near-freezing and near-toxic conditions. All day, we kept seeing flamingoes in lakes which had a crust of ice around the outside (apparently the flamingoes only migrate south to Chile when the temperatures drop to -15/-20 degrees Celcius, and the lakes actually freeze), and most contained high concentrations of arsenic, sulfur, and borax. <Aside: who knew borax occurs naturally, in large quantities, and just deposits itself on shores of lakes???> One lake even had “no smoking” and “skull and bones” signs along the shore – just what is IN that water?! However, the flamingoes themselves were so gorgeous and a little bit funny, wading around with their backwards knees, fishing around for algae and small microorganisms (the water is too toxic for fish). I could stare at them forever, but the wind was vicious, so at most stops we only got out long enough to take a few pictures. This day made me very glad that I stocked up on warm clothing when I packed. Layering works wonders!!
We also visited a few lava formations. The first looked very much like a lava field, with solidified but brittle waves. Just as we were wondering which volcano it would have come from (there were many to choose from in the near vicinity), the guide explained that this was actually formed when the plates collided and mountains were also formed, and magma spilled out directly. The second had a much smaller area, and was much more individual – whereas the first was a field, the second was a collection of free-standing monoliths which had been eroded by wind into pretty cool shapes. As for the volcanoes, apparently there is a currently-active one of the Chilean side, but all we could see of it were a few steam plumes. I expect more of my active volcanoes!!
On the last day, we were pretty busy as well. Our first stop was geysers, although in my non-edumacated opinion they seemed to be more steam vents combined with sulfuric pools of bubbling water. I always thought a geyser has to involve water shooting out, not just steam (Dan disagrees, wikipedia seems to agree). Still an incredibly cool site, though, especially back lit by early morning sun with silhouettes gliding through the steam. Our next stop was at a fabulous hot spring. Undressing to get in was quite cold (it had gotten down to -3-4 degrees that night, and this was only around 7:30 or so), but sitting in there to thaw out was pure bliss. We had a beautiful view, as well, of a lake with flamingoes shrouded by patches of steam of the hot spring. These guys were a little bit smarter than your average flamingo, living in a lake surrounded by hot springs, and so significantly warmer than all the rest.
Throughout the trip, what never ceased to amaze were the mountains. We actually covered a lot of ground over the three days (it took nearly 8 hours to drive back to Uyuni on the last day), and the shapes and colours of the mountains were always changing and always beautiful. Definitely the most scenic area we´ve visited so far!
