Day 10 - "You've got to throw it in there, Mr Frodo!"

If yesterday was my specialist interest, then today was Carolines. We were staying in Volcano village, a mile or two outside the Hawaii Volcanoes National Park. The Park is home to several volcanoes, including Kilauea which has erupted continuously since the early 1980s.

The UK is quite lucky in that it really doesn't have weather or geology that the rest of the world has to deal with. We don't have extremes of cold or heat, high mountains or earthquakes. Therefore, when you get presented with some Real Live Geography, it can be difficult to comprehend or even describe.

We were lucky in our timing, as one of the craters that form Kilauea, the Halema'uma'u had started smoking quite actively. When I say Kilauea had been erupting, I don't mean firing great gobbets of lava a thousand feet into the sky, the lava is elsewhere. Instead, the crater has been emitting tons of volcanic gases into the sky. Normally it just smokes quietly to itself, throwing out gas, including about 20 tons of sulphur dioxide a day. When the wind blows this emission over the land, the locals called it volcanic smog or "vog". Now more active, Halema'uma'u was pouring over 1500 tons of SO2 into the atmosphere and if the wind was in the wrong direction, the vog would cover Volcano village. As we were in Waikiki, we saw reports that due to the northern tradewinds dying out before switching to a southerly direction for the next few months, the vog was settling over Volcano, the park was closed and residents advised to stay inside.

Thankfully the winds had picked up when we arrived and the gas was being blown SE, forcing the closure of a large part of the Crater Rim Drive but giving some perfect views of the crater from the Jagger Museum.

To witness the sheer pent up power of a volcano is an unforgettable sight. The hole blasted in the side of the crater is only 35 metres wide, yet it was pumping gas out at a huge rate and forming spectacular clouds. The trails leading across to the crater were closed, but the museum had provided several sets of telescopes for close up viewing. Inside, you could see the live readouts from the seismic monitors, measuring the contraction and expansion of the very ground beneath your feet - the overall effect was difficult to comprehend as the instruments indicated that the place you were standing on was actually rising. Although Halema'uma'u is not spitting out lava, it was only 2km below the surface.

That one volcano is just a small part of the park. Along with steam vents (where rainwater is pushed back above ground by the heat) and sulphur banks, there is the Thurston Lava Tube. A lava tube is a sort of tunnel through which the molten lava flows. The Lava Tube is about 300m long and lit so that you can walk through. You might think that an underground cave would be quite small, but in places the tube is 21ft high and never less than about 12ft. To stand in the tube and imagine the sheer amount of liquid rock that must have flowed through there is mind boggling.

You get to the Lava Tube down the Chain of Craters Road. This is the old Highway 130, passing the craters of many past volcanoes, leaving behind huge 600ft cliffs. Every so often, the road is just surrounded by black rock, the remnants of lava flows from the past 20 or 30 years. Again the sheer scale of the devastation has to be seen to be believed.

We didn't make it to the end of Highway 130 - because as darkness fell, we had to get to the other end of Highway 130. Which sounds confusing until I explain that in the 1980s, a particular eruption of Kilauea flowed right across Highway 130, splitting it into two. Repair was impossible as it wiped out about 10 miles of road, as well as an entire town called Kapalana.

I mentioned that Kilauea is still erupting - this is evidenced by the activity at Kalapana. Lava is flowing along lava tubes for about 10 miles or so until it hits, quite literally, the Pacific Ocean. At Kalapana you can walk across the old lava field until about two miles distance where at night, you can see the red hot glow and steam of lava meeting water.

One of the most explosive combinations possible is something super hot hitting water, especially if the water has nowhere to go. For example, when the Space Shuttle lifts off, there are huge plumes of smoke and steam. This is from the water below the launch pad - the rocket exhaust instantly turns the water to steam which then blasts outwards.

The Halema'uma'u crater is a creation of lava hitting water. The area was regularly a lake of molten lava that would rise and fall like the water level in a sink. Eventually the lava fell through the bottom of basin onto water collected below. The resulting explosion created the Halema'uma'u crater, some 200 feet deep and over a quarter of a mile across. Rocks were found four miles away. That is the sort of explosive power of a volcano, and Kilauea isn't even a big volcano.

The drive to Kalapana is much trickier than the Saddle Road and I was grateful to be in a 4WD. At the 22 mile marker, the road literally stops. The lava flowed directly across Highway 130, destroying everything, including the town. (There are stories of the residents throwing propane tanks in front of their houses. They were not insured for volcano damage, but they were insured for fire. If they could get the tanks to ignite the house before the lava took it, they could make a claim.)

The drive across the lava is at least two miles, before you get to a car park. The attendants check you have water, a flashlight and decent footwear for the mile walk to the viewing area. People without lights or wearing sandals are not allowed. The walk is comparatively tricky, stepping across cracks and around boulders and the absolute darkness doesn't help.

Eventually we reached the shoreline and turned off the lights. There is no mistaking where you are supposed to look - the only thing in the pitch black darkness is the red glow in the distance. As you get accustomed to the view, you pick out individual plumes of steam as three or four active tubes vent directly into the Pacific.

The sight is more spectacularly as the lava drops ten or more feet into the water. I could pick out not only the steam but occasionally lava itself, spat back by the reaction against the water. Given the distance from the site, I cannot begin to work out how big those chunks of rock must be in order for me to see them from two miles away.

This is the process of building land, as Kilueaa has created 200 acres of new land in 20 years. If you ever want to feel insignificant, to put the problems of the world into perspective, go watch a volcano busy creating an entire country.