My time in Yellowstone is a tale of two days. The first was 28th July, when I drove from my previous night's stopover in Billings, Montana to the north entrance of Yellowstone National Park.

The park itself is huge, so I decided to split it into two days' worth of exploration. On the first day, once I'd got to it, I would go down the east side of the figure-eight loop road. And, since I was staying outside the west entrance of the park, on my second day I would explore the west side of the park.

Day 1

On the first day, as I said, I saw the east side of the park. After the second day I decided that this area contained the most beautiful part of the park that I'd seen. It has the spectacular mountains and valleys in it. I saw some waterfalls but, for a change, skipped the hike down to the foot of the falls. That was after seeing the people coming back up from it panting for breath.

The park is very busy - it is teeming with people and cars. At the canyon section, where I could gaze upon the Grand Canyon of the Yellowstone, there was a throng of people at the easy-to-get-to overlook at the top of the Upper Falls. But when I took the mile long trail to the top of the Lower Falls I saw only about twenty people the whole way there and back. I was glad to get away from the crowds for a while. And the view was absolutely stunning. As well as the falls the view went all the way down the canyon and it had such vivid colours. It is the most famous and photographed part of the park.

After I'd taken my own photos I asked a girl who'd arrived at the viewpoint just after me to take a photo of me with the background. She happily obliged and we walked back to the parking lot together. And then she did something totally unexpected - she reached into her truck and pulled out some brownies she had made and gave them to me. She said that because I'd been travelling for so long it would be good to have some homemade food for a change. Then it all goes fuzzy and the next thing I know I'm waking up at the bottom of a ravine with a kidney missing. No, really, the brownies were delicious! And not laced with any kind of drug at all. So thank you, Carla, if you're reading this, it was very generous of you.

As well as the canyon I also got to exercise some more of my senses at the Mud Volcano and Sulphur Cauldron. That area is where the mud pits and various bubbling features are. And they all smell sulphurous, like slightly rotten eggs. My favourite was the Dragon one which did look and sound like a cave containing a dragon. The gas bubbling up from below the earth's surface came up inside a small cave and it belched steam so it looked and sounded like a dragon was in there.

There were also some encounters with wildlife. A couple of times I had to stop on the road because the cars ahead had stopped to admire the grazing bison. On day two I got my own back by eating some bison chili for lunch. Yum!

Day 2

Day two actually came two days after day one because I wanted to make sure my birthday was somewhere good. So that was when I came back into the park for my western side expedition.

I started at Old Faithful, which was massively built-up. The road leading to it became a four-lane divided highway and even had an off ramp instead of a plain intersection. I've never seen a road that developed in a national park before. That gives you an idea of how popular the place is.

I checked the prediction schedule for the geysers and sat down on one of the dozens of benches set around the Old Faithful geyser. I was joined by a nice old lady called Joy who talked to me as we waited. She was a fascinating person. She was a senior citizen (my polite way of saying 'old') and on a road trip with her friend from Florida - check a map and you'll see how far that is! She's also been on a rafting trip in the last few years down some rapids. When I reach retirement age I want to be doing stuff like that!

There were several false starts to Old Faithful - it's such a showman! - but when it finally blew its top it was really impressive. I walked around the area and saw many other features - either geysers that weren't currently active or colourful springs.

By luck I arrived at Riverside Spring just before it erupted. I thought it was better than Old Faithful, partly because it went on for about fifteen minutes - so long that I got bored and left it - and partly because it was sat right on the bank of a river which was a peculiar location.

There were several other sections of geysers and springs along the loop road. I nearly skipped them but decided I might as well stop at each. And I'm so glad I did. At the Midway Geyser Basin I discovered the Prismatic Geyser Basin. In that one place are all of the most beautiful colours known to nature. And there were massive clouds of steam constantly coming off it, and from the nearby geyser. It was a bizarre sensation because at first the steam would wash over me with a warm blanket-like feeling and then it stopped but the wind continued and, because I was coated in moisture, I felt freezing cold for a few seconds, and then it repeated.

The trouble for me was, once you've seen a dozen geysers you've seen them all. Unless they're erupting at the time, of course. Then it's awesome! Just like the two I came across in one section that seemed to be continuously spewing water.

In my quest to find a Wyoming state souvenir I had to venture to the northern end of the park to an open gift shop. They didn't have anything Wyoming specific though, but the drive there and back was worth it because again I got some views of the great mountains and valleys that I had loved from my first day in the park. I decided the north part was my favourite, although I had like the hydrothermal features of the southwest.

On the drive back south down the park I saw the most perfect, beautiful sunset. The sun was a large red ball half covered by the tops of the mountains and shining down over green, lush trees, with four beams of light at equal angles apart breaking through the higher clouds. It would have made the most amazing picture but there were no stopping points there and, by the time I came to one, I'd descended a few hundred feet and the sun was no longer visible. So I'm sorry you can't share in it, but I saw it and have the memory and, since I'm paying for this trip, I think that's only fair. Yellowstone gets my thumbs up as a good national park. If I'd had a third day I would have done a longer hike into the backcountry to see something more special away from the crowds.

While visiting the park and my side-trip to Idaho I stayed in Madison Hotel in West Yellowstone, Montana (one mile from the park and Wyoming state line). The hotel dates from 1912 and the room I stayed in was great. It was tiny by modern hotel room standards but it was all wood and it actually had a woody smell to it, which was pleasant. One time, when I was coming down the stairs to leave, a couple, who had been admiring the lobby and gift shop area, asked me what it was like staying there. I described it and made it sound good. But that night when I went to bed I realised I had left something quite crucial out - the sound insulation between rooms is very weak. As I sat there I could hear the guy on one side snoring and the guy on the other side being sick. Nice! Maybe he ate some bad seafood.

The town of West Yellowstone is quite nice. It's got some nice old buildings, some of which are probably fake. But it looks like a real western town. And a couple of the streets are busy with people late into the evening as people buy all kinds of gifts.

Thanks to everybody who sent me birthday wishes. (Hopefully that gets me out of replying individually to each of you.) Be sure to check out the two photo albums and two videos for this Yellowstone blog.