Day 45 - Thermal Explorer Highway, North Island, New Zealand

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Thursday January 2nd, 2014. Thermal Explorer Highway to Rotorua, North Island, New Zealand

Really long blog - sorry but all this seriously rocks our Geographer Boats - and we want a comprehensive record of what we did for when we get back!! Skip to the photos now if you like.

Having had a lovely, laid back and relaxing, couple of nights at Taupo our plan for today was to head north through the volcanic area to Rotorua. We were largely following a well signposted route called the Thermal Explorer Highway (TEH) which was marked by cute little brown signs with a geyser on them. (The Pacific Coastal Highway that we followed previously was marked by blue signs with a wave on them by the way). Before we joined the TEH we headed out of town where we stopped at a viewpoint over the lake and took a few snaps. Then we headed to Huka Falls which are, apparently, Nz's best known falls. Here, not far from their source in lake Taupo, the waters of the Waikato River rush at almost 250,000 litres (two Olympic-size swimming pools) per SECOND through a sudden chasm and leap over an 11 metre ledge to foam in a deep semicircular basin. We arrived and found a parking place no problem. We walked over a bridge which crosses the chasm just above the falls. Once on the other side there are a number of viewing points. The roar of the water was incredibly loud. Unfortunately one of the things that doesn't come across in a photograph are the sounds. It was a really impressive site to see the water swirling along and tipping over the edge into a foaming bright blue pool.

A couple of kilometers up the same road we joined the TEH. The guide describes this as "a road trip that's jam-packed with awesome things to see, do, taste and even smell". Our first stop was the Craters of the Moon, a volcanic area just outside of Taupo. We paid our entrance fee and proceeded into the area. Here there are boardwalks around a fragile thermal environment which prevent visitors accidentally straying onto soft hot ground and getting burns. The largest crater on the left as you go into the park last erupted in 1983 and pumice stones are still clearly visible. Activity in the thermal area changes and shifts over time and the boardwalks have been moved away from particularly hot areas. We could clearly see the ones that had been moved - often a number of times. The thermal activity at the Craters of the Moon is monitored regularly by scientists from the Institute of Geological and Nuclear Science.

We walked around, stopping at the various lookouts and taking photographs. The 2 craters past the first lookout last erupted in September 2002. It was the biggest eruption in a decade. The paths and boardwalks were covered with mud, ash and pumice to a depth of 5 cm (2.5 inches). The large mud crater at the 3rd lookout frequently erupts pumice and mud. Eruptions occur when steam passages, well below the surface, get blocked by mud after heavy rain or by earth movements. At the back of the area there is a loop which takes you to a higher level to the crater rim. it is quite a steep uphill climb but gave us great views over the whole area. We could see the fumaroles all over the park and hear the ones immediately below us which were roaring as the steam came out.

We left the park and a few kilometers down the road pulled off the roundabout to take a look at the Waikato Geothermal Power Station 7 kilometers north of Taupo. Then continued on to the Hydro-Electric Dam on the Waikato River. They only let the water through about 6 times a day, and we were lucky enough to arrive when this was happening. The water came through in torrents and we could see this clearly from the road bridge that lead to the car park. We crossed the road and could see the waters tumbling away down the valley.

We drove north for half an hour to our next stop which is called Orakei Korako ("The Place of Adorning"). This place is also known as 'The Hidden Valley' and has remained completely unchanged for thousands of years. It is a thermal 'theme park' (not literally!) with more active geysers (pronounced guy-zers)- at least 20 - than any other geothermal field in NZ. At Orakei Korato (OK), 20 million litres of hot water flow over silica terraces every day. We parked the car and had a picnic lunch looking over the Lake Ohakuri where there were waterskiers, jet skiers and power boaters having a great time. We could also see the steam rising from the geothermal area on the other side of the lake.

After lunch we purchased our tickets and waited for the ferry to take us across the lake to the geyser valley and caves that make up OK thermal area. Once off the ferry we could smell the sulphur immediately. At the top of the jetty we could see the boiling water tumbling down into the river below. The tumbling waters had deposited minerals which created silica terraces, which are reported to be the largest of their kind in the world. We followed the boardwalk which was punctuated with warning signs not to stray "as hot steam burns". The Emerald Terrace (the largest of its kind in NZ) has a thickness varying from 20 mm to 20 metres,continuing another 35 metres under the lake.

On our right we passed the Diamond and Saphire Geysers which let off steam when they feel like it. Nobody knows when the Diamond Geyser will erupt but when it does it will last a few minutes to several hours, ejecting boiling water as high as 8 metres. It gets its name from the way it shatters its water jet into millions of droplets which sparkle like diamonds in the sunlight. Sometimes this geyser will sit dormant for a period of time and the Sapphire geyser will play five metres further along the walkway. Its eruptions occur every 2 to 3 hours.

We continued on the path until we came to Hochstetta Cauldron. This is a steaming, bubbling mud pool that smells terrible. We climbed up to the Rainbow lookout where we had a better view of the Caldron and great views over the river and entire thermal area. Next we passed a spluttering orifice called the 'Devil's Throat', before arriving at Rainbow and Cascade Terraces created by a huge earthquake about the time Lake Taupo was created. We really were in a geographer's paradise (lucky we are both geographers!). The unbelievable colours have been formed by the hot water algae growing in temperature of up to 60 degrees centigrade. At the base of these terraces there are several small geysers and to the left the aforementioned Hochstetter Pool which was named after the Austrian geologist who visited here in 1859. It erupted in November 1954 and played as a geyser until 1955 but ceased activity after swarms of subterranean earth shocks were felt.

One of the fault scarps was called 'The Golden Fleece'. It is 5 metres high and 40 metres long and was formed around 131 AD. Numerous geysers have erupted at the base of the right hand corner, making the area highly unpredictable. We walked past Elephant Rock which looks like (you guessed it) an elephant and walked onto a terrace which was called the 'Artists Palette'. Formed by hydrothermal eruptions between 8000 and 14000 BC, the Artist's Palette remains today one of the most dangerous and unpredictable areas on the resort. The thickness of the silica in some places is as little as 20 mm. Activity varies so much, that at times the springs discharges masses of hot water which cover the silica flat creating ideal conditions for algae growth. The myriad of browns, greens, yellows, oranges and pinks, pock marked by many crystal clear blue pools, transform this into a really beautiful area.

We started to climb the hill towards the 'Sacred Cave' when the Diamond Geyser blew its top! We were too far away to run back to see it but could see the water spout above the trees. D took some snaps. We reached the 'Sacred Cave' which is sealed off because of dangerous rock falls. Inside there is a plaque marking the deaths of two Maori brothers who died in WW2. The cave was a special place for them which is why their family laid it here. Unfortunately nobody can see it anymore so there is a photograph of it on the lookout point. While we were reading the information one of the other visitors noticed that there were a pair of owls with a chick sitting on a tree just outside of the cave. We took some fairly grainy, distant shots of them. The Sacred Cave is one of only two geothermal caves in the world (the other is in southern Italy). It is still not known exactly how these caves are formed.

We went next to the 'Mud Pools'. Mud pools form in places where the thermal fluids have chemically decomposed surface rocks to form clay. This clay is heated by the underground energy source and boiling mud pools are created. Activity varies from season to season, depending on the amounts of rain to moisten or dry the mud. For this reason, mud pools generally appear more active in winter than summer. We finished off passing the 'Soda Fountain' on the way back to the jetty. After laying dormant for 17 years the 'Soda Fountain' suddenly refilled and burst into life in 1984. Since then it has been unpredictable and can fill and empty at any time. It didn't do anything when we were there. When you reach the jetty you can ring a bell to call the ferry to come and pick you up. We didn't have to bother as someone else had already done it - so we just boarded the boat and returned to the car park.

We returned to the TEH and continued north towards Rotorua. On the way we stopped at Wai-O-Tapu Thermal Wonderland (W-O-T). We had been here before in 2008 but had not managed to do the whole of the area due to lack of time (we had to catch a cruise ship and return a hire car!). We decided to do it again just to compare it with OK which we had thoroughly enjoyed. WOT thermal area is part of a Scenic Reserve administered by the DOC and has the largest area of thermal activity of any hydrothermal system in the Taupo Volcanic Zone.

Covering some 18 sq kilometers, with the volcanic dome of Maungakakaramea (Rainbow Mountain) at its northern boundary, the area is literally covered with collapsed craters, cold and boiling pools of mud, water and steaming fumaroles. The area that is open to the public is only a small proportion of this. The volcanic activity here goes back 160,000 thousand years and is located on the edge of the largest volcanic caldera within the active Taupo Volcanic Zone. The WOT stream ultimately drains into the Waikato River and out to the Tasman sea. However there are no fish in the WOT stream due to the numerous minerals which are introduced into the water by boiling springs and volcanic gases.

We paid the entrance fee and went into the "Thermal Wonderland". The first thing we came across was "The Craters". These are up to 50 metres in diameter and up to 20 metres deep. Several contain hot water springs and most have extensive sulphur depoists formed by escaping vapours meeting with the atmosphere. mosst of these craters have been formed over the last few hundred years by the action of acidic stream water rising from superheated under-ground water dissolving the ground above and ultimately causing it to collapsed.

We continued along the path and came to something called "The Devil's Home". This is a collapsed crater where underground acid action has caused the ground to collapse. It sides are yellow/greenish where they have been coloured by cooling volcanic vapours. Oh we do love all this!

The next crater was called the "Rainbow Crater", named after the sulphur crystals and coloured mineral veins exposed in the kaolin (china clay) walls of the crater. We could see the oily slick on top of the boilding water at its base. The water resembled a boiling mud pool but apparently in the winter it is more fluid. Opposite this crater is area of fumaroles where crystals are forming around the vents. After the "Rainbow Crater" was the "Thunder Crater" which is a crater that collapsed in 1968. Its collapse was caused by steaming water eroding the bottom - just shows how unstable these thermal areas can be!

Further along the walkway we came to the next 'attraction'. This was a series of mud pools called "The Devil's Ink-Pots". The water levels in these pools fluctuate with the amount of rainfall. Their black colour is due to the small amounts of graphite and crude oil brought to the surface by hot water forcing its way up.

Then we came to another "Artist's Palette". Wonder who pinched the name of who? Anyway you would have thought one or other of these enterprises could have been more imaginative - what's wrong with "Painters Paintbox" or such like? The Artist's Palette here is formed in much the same way as at OK. The overflowing water from the Champagne Pool is responsible for dumping the coloured minerals here.

We strolled along in the sunshine until we came to the "Opal Pool". This is a sulpherous (spell checker came up with super heroes which made M smile!) spring on the edge of a terrace and is named after its greenish yellow colour. M's opal isn't yellow at all but more of milky white greeney blue. D commented that it wasn't very "opal coloured". We had a great view of the silica terraces and down the valley from here. We could see the steam from the Ohaaki Geothermal Power Station in the distance.

We crossed the terrace by means of a boardwalk. This structure, we were reassured by the blurb, sits on the very edge of the firmer ground associated with the silica terraces. It rests on specially treated timbers and is secured by stainless steel pins - reassuring! From the boardwalk we could see the "Primrose Terrace". these sinter (volcanic ash) terraces are the largest in NZ since the partial destruction of the Pink and White Terraces in the eruption of Mt Tarawera (1886). The water from the Champagne Pool contains dissolved silica which, as the water evaporates, is deposited as siliceous sinter. They are regarded as being very fragile and have been forming at a variable rate over the last 700 years currently covering an area of about 1.5 hectares (3 acres).

We passed the now dormant (but maybe not for long) Jean Batten Geyser which is named after the famous Rotoruan aviatrix who visited WOT in 1931. She was famous for her solo flights and became the first woman to fly both ways between Australia and England in April 1935. The geyser has been known to erupt to about 3 metres high but it hasn't played ball for a few years.

After the geyser we walked along the Sacred Track which winds its way through some native bush that links the boardwalk with the panoramic view. It passes the site of what is believed to be an early settlement. The site is marked by some Rhododendron trees. At the top of the track we reached a lookout which afforded us great views of Primrose Terrace. Then we came to a Panoramic View of the Kaingaroa forest, which is the largest man-made forest in the Southern Hemisphere, and covers the Kaingaroa Plains. In the distance we could see the Ohaaki Geothermal Power Station. The green waters of Lake Ngakoro (the grandfather) cover about 12 hectares and takes the water that has flowed across Frying Pan Flat from the direction of the Champagne Pool and Lake Whangi-o-terangi (colour of the sky). This blue lake covers about 5 hectares and the colour is due to the mineral particles being suspended in its waters.

Following the path the next stopping point was the Bridal Veil Falls. These falls mark the end of the Sinter terraces and have been partially coloured by the overflow from the Opal Pool while the green colour can be attributed to microbial mats. From here the water flows into a shallow creek as it makes its way southward towards Lake Ngakoro.

Last time we were here we crossed over straight to the Champagne Pool and missed the next section of the Thermal Wonderland due to lack of time. This is the section called Walk 3. This time we had the time to complete this walk. We passed the WOT Geyser which erupts to 3 metres on a cycle from 2 to 36 hours when the water table is low. It didn't do anything while we were there. The track took us past the Alum Cliffs which are shallow horizontal ridges sculpted by ancient weathering. Opposite the cliffs is an eruption crater with an acidic lake which is about 700 years old.

We continued on Walk 3 until we came upon the aforementioned "Frying Pan Flat". This is also an eruption crater, the unstable floor of which is littered with bubbling hot springs and fumaroles. The track changed back to a timber boardwalk and from here we could see the "Oyster Pool", named because of its distinctive shape. The boardwalk ended and changed back to a track. The next 'attraction; was the Sulphur Caves which are magnificent examples of undisturbed crystallized sulphur formed as hot sulphur gases have cooled in the sheltered atmosphere of the overhanging cliff.

At this point the track went off to a dead end. We followed it and came to Lake Ngakoro Waterfall. This waterfall tumbles over the rocks into the emerald green waters of Lake Ngakoro (the grandfather). From the lookout above the falls we could see most of the lake. This lake was formed after an eruption more than 700years ago. The steam rising from the left hand shore of the lake showed us that the land around it is still active.

We retraced our steps to the main track which took us on a Native Bush Walk which is representative of the marginal forestry land in the area. It follows a ridge through a stand of giant Kanuka Trees before dropping down into the valley which links Echo Lake with Frying Pan Flat. The high canopy and the natural water courses proved an excellent habitat for native Bellbirds, Tui's and Fantails that live in this area. We shortly came across the "Sulphur Mounds" which look like large yellow mole hills. These mounds of sulphur were formed under water and were exposed when the area was drained in order to build roads in the 1950's. At the end of the bush walk we re-joined Walk 1 at the Champagne Pool.

The "Champagne Pool" is the largest spring in the district being 65 metres in diameter and 62 metres deep. Its surface temperature is 74 degrees and the bubbles (from where it got its name) are due to carbon dioxide. The pool was formed 700 years ago by a hydrothermal eruption - the rocks from which can be seen at the top of the embankment by the track. Minerals contained in the water are gold, silver, mercury, sulphur, arsenic, thallium, antimony and others which are presently depositing in the surrounding terrace ledge. The various terrace ledges have been associated with tilting of the pool as a consequence of earthquake activity.

We were nearly at the end of the tour but were in for a few treats yet. First there were a couple more craters. The "Inferno Crater" has a bottom of violently boiling mud. The "Birds Nest Crater" is so called because Starlings, Swallows and Mynahs nest in the holes in the walls of this collapsed crater. The heat from below rises up the crater walls and incubates the eggs.

Next to last was the "Sulphur Cave" where sulphur crystals have made beautiful formations on the cave wall above the vents. Last but by no means least was the "Devil's Bath". This is a large crater filled with the most amazing emerald/bright yellow coloured water. The colour is the result of excess water from the champagne pool mixing with sulphur and ferrous salts. Changes in colour through green to yellow are associated with the amount of reflected light and cloud cover. Today it was a vibrant emerald green.

We found the YH no problem had a good meal with the usual vino. We retired with our boats still seriously rocking. We have more thermal stuff to look forward to tomorrow too - yipee!!! (Bet you all can't wait!)





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