Most people don’t know much about this volcano. Because most of the upper slopes are privately owned, very few have had the privilege to visit Kaupulehu. Recently, Hawaii Forest & Trail was granted permission to lead tours behind the locked gates of Hualalai. In a short 30 minute drive from the hot, dry, coastal lands of the resorts you’ll climb to an elevation of 1800 meters where the cool mountain air and native forest plants create a striking contrast. And it is here where some of the most recent eruptions of Hualalai occurred around 1800 A.D. Dramatic craters, eruptive fissures, lava tubes, spatter ribbon, cinders, Pele’s tears, and lava channels are just some of the spectacular formations to discover here.

The most striking volcanic features you encounter are the dramatic craters. Hawaii’s volcanic craters form in three different ways. On Hawaii Forest & Trail’ short nature walk all three types of craters can be seen. Understanding how these craters were formed is
a great way to learn how Hawaiian volcanoes erupt.

The first crater at the start of the walk is actually a series of several craters in a line. They are unnamed and are the remnants of the collapse of the eruptive fissure of the 1800 eruptions. As you stand at the edge of the 120 meters deep crater, you are looking at a place where magma came out of the ground in a long line running 2.5 km down the mountain. The lava was shot up in the air by the expanding gas and formed a “curtain of fire.” These types of eruption sites are called fissures. Many of Hawaii’s eruptions are fissure eruptions. The lavas from this fissure flowed down the mountain all the way to the ocean. The lava flow is one of the largest flows on the Kona Coast. After the eruption was over, the fissure collapsed in on itself forming the line of craters. Still present around the craters are channels where the lava began its march to the sea and lots of tephra. Tephra is any lava that moves through the air, usually propelled by expanding gases.

Cinders are the most common tephra to be found on the trail. Cinders are small and airy pieces of lava that are cooled and solid by the time they hit the ground. Cinders are light because they are full of tiny holes that once held gases. Think of cinders as lava popcorn. Another kind of tephra, one of my favorites, is ribbon spatter. If cinders are like popcorn, spatter is like hot taffy. Globs of lava are thrown into the air and as they return to the ground they stretch and fold and hit the ground in a very plastic state. Ribbon spatter is spatter that has long and sometimes curled or ribbony strands attached to them. There are many beautiful pieces of ribbon spatter all around the eruption area. Pele’s Tears are also easily found along the trail. Pele’s Tears are tiny tear-drop shaped pieces of lava. They are similar to cinder but are denser. As they fall through the air, they are aerodynamically shaped with tiny comet like tails. It is a lot of fun to search through the cinders to find these pretty, shiny, black tears of Pele.

The second crater seen on the nature hike is Kaupulehu. Kaupulehu Crater, like the fissure craters, is an eruptive site. But this crater wasn’t formed by collapse after the eruption; it was built up during an eruption. The crater is in a Spatter Cone. A spatter cone is formed from a lava fountain erupting from a single vent, unlike a fissure eruption which is a long series of vents or openings. The spatter from the fountain falls back to the ground and builds a cone structure around the vent.

Looking down into Kaupulehu is like looking at an empty bathtub, complete with drain, overflow, and bathtub rings. As lava erupted out of the ground it formed a hardened cone around the vent source, building higher and higher. The first eruption and construction of the Kaupulehu cone happened several thousand years ago. In 1800 A.D. the vent opened up again and lava began to fill the crater inside the old cone. As the eruption continued it eventually filled the crater with about 25 meters deep of lava. At one point the level rose higher than the side of the cone and overflowed down the cone creating a small lava flow. At the end of the eruption, the remaining lava drained back down the vent leaving the present crater. Standing on the crater rim it is easy to see the rings of hardened lava that show us the various levels of the lava pond during the eruption. You can see where the lava overflowed the rim. And the vent, or drain at the bottom of the crater, looks as if the draining lava was frozen in place as it descended into the great, dark, hole. Kaupulehu Crater is very unique. It is one of only two known eruptions that occurred in older cones. It is very unusual for lava to reoccupy a previously erupted vent site.

Near the end of the walk, the third and final crater seems to appear from nowhere. This is a pit collapse crater and is different in creation and form than the first two. This is a crater not directly related to an eruption. It is uniformly round and nearly as deep as it is wide, over a 100 meters across and nearly 100 meters deep. Geologists unofficially have named the crater “Lua Manu Aloha”, which literally translated means the Aloha Bird (manu) Pit (lua.) Often when you first approach the crater a flock of exotic parrots who nest in the crater walls take flight and with raucous alarm calls begin to fly up and out of the crater.

Because the crater is so deep, it takes the birds a few spiral laps inside to get up and out of the crater. Lua Manu Aloha formed in a dramatic collapse several thousand years before the 1800 eruptions. Pit collapses form when magma once stored underground either drains away or erupts out. This then leaves a void underground. The ground above the empty space is unsupported and collapses. At the surface these collapses manifest themselves as deep pits. The sides of the pit craters reveal many layers of lava flows and offer a vivid example of how our islands have been built up over time one lava flow after another.

Along with the different craters another feature at Kaupulehu are a series of lava tubes. Lava tubes are caves that form during the flow and become conduits for transporting the lava from the vent source down slope underground. As lava erupts out and is exposed to air, it begins to cool and crust immediately often developing frozen banks which channelize the flow. Soon the lava is flowing like a river in the channel. Over time a skin crusts over the channel and eventually the lava is moving under a roof creating a tube. Molten lava is around 2000 degrees Fahrenheit and has the consistency of wet concrete. The flowing lava melts and grinds away the floor in the channel or tube making them deeper over time. When the flow is over, a lava tube cave is left behind. As the caves cool, cracks form in the hardened lava, and sometimes sections of the roof cave in. These roof openings are how we see into and enter the caves. On Hawaii Forest & Trail’s walk several lava tubes are seen. Some of them are small, only a meter or two high. But some are large enough to explore. One short section of a large tube allows the hiker to enter and exit the cave without needing a light. It has different kinds of stalactites and other cave features which are great visual aids in understanding the formation and structure of Hawaiian lava tubes.

Kaupulehu is truly an outdoor classroom of vulcanology. In a few hours time and within a short walking distance, the mysteries and wonders of Hawaii’s volcanoes are explained and revealed. Kaupulehu is a place the Hawaiians called the wao akua-the region of the gods. It is a strikingly beautiful place, a surreal landscape of lava, forest, mist, and craters. It is such a special place that Hawaiian royalty chose these lands as their own and today it is still owned by the Kamehameha Schools Trust. The ability to visit these private lands by exclusive access with Hawaii Forest & Trail is a unique and splendid opportunity.