Tem42 has covered pahoehoe very well above, but please excuse me an anecdote.
Flowing pahoehoe is possibly one of the most beautiful things in the world.
Let me back up. A while back, I was in Hawaii with my wife. We went to Volcano National Park, and the only thing going on beside the usual sulfur vents, etc. was a steam plume from where lava was running into the ocean. We decided to walk out to the closest safe place and timed it so that the hike would get us there near dusk. We watched as the plume turned from steam-white in the sun to bottom-lit by staggeringly hot rock red in the dark, and then walked back out at night. This was a popular thing to do, so there was a stream of people with flashlights headed in either direction on a path marked out in advance. From above, I'm sure it would look like some sort of thrill-seeking ant trail.
On our way back in the dark, we looked across the expanse of volcanic rock and saw glowing red on the slope in the distance. Why, there was perfectly serviceable lava over there, why would they just point everyone to go and watch well-lit water vapor?
A few days later, we returned to the park with the idea of hiking up and seeing the lava. We went into the main visitor center, staffed with helpful rangers, and inquired about it. We were told, flat out, there was no way at all that we would be allowed to. Absolutely not. Would you like to buy a map or a book about the park?
We drove down to the impromptu parking lot near the active area, which was created after the road further down was covered in lava a while back. We went to the impromptu ranger station and approached someone. We told them what we wanted to do. Rather than blowing us off, they grabbed another ranger and the interrogation began.
"Let's see your shoes." We showed that we were wearing sturdy boots which protected and supported the ankle.
"You know how far it is?" We didn't, but they helpfully told us.
"You've hiked on lava before?" We told them we'd walked out to the sea vent and knew how hard hiking on hilly broken black glass was.
"Let's see your lights." We showed them the trio of fairly powerful flashlights.
"Let's see your water." We opened our backpacks and showed them that we had 4 liters of fluid each, 2 of water and 2 of sugary lemonade.
"Let's see your food." We showed them the various granola bars, nuts, etc. that we had.
There were a couple of glances and shrugs between rangers, which appeared to settle it. They gave us detailed instructions with visual landmarks of how to get up there, how to approach the flow from the side, how fast a'a lava could go downhill, and every other safety precaution they could think of. They wrapped it up with something along the lines of "Most of us have been up to that flow, but that doesn't mean that it won't kill you."
With some variation of "We never spoke, we were never here" we were on our way.
We got up to the altitude of the flow with only humorous problems (Seriously? Who thinks a bee hive is going to be in the only thousand square feet of non-rock on many, many square miles of volcanic glass?) When we got to that level and looked across, there was nothing but the wavering distortion of air caused by the lava's heat.
We began picking our way in that direction. Based on the heat, we kept picking our way uphill. We wanted to find the leading edge where there wasn't potentially lethal fresh lava uphill from us. With a little bit of effort, we found it. A massive field, obscuring the horizon with its heat, nipping at our shins while we tried to photograph the tiniest rivulet on the leading edge.
It was gorgeous.