If you are planning a trip to Hawai’i Volcanoes National Park, it helps to have a rudimentary knowledge of some of the terms, landforms, and objects you will see. This short, simple primer should help you identify what you are looking at, as well as provide an understanding of the mechanisms which created what you see.

Day's end at Kīlauea volcano, Hawai'i Volcanoes National Park / Rebecca Latson

But first, a little bit about pronunciation. With the Hawaiian language, every vowel is sounded out.

A = ah like “above”
E = eh like “let”
I = ee like “easy”
O = oh like “hole”
U = oo like “shoo”

For instance, Kīlauea is pronounced (kee-laow-weh-uh). That line over the “i” means you should extend the sound a little bit. ‘Ōhi‘a lehua is pronounced (oh-hee-ah leh-hoo-ah). That apostraphe in front of the “o” and the “a” is a glottal stop, or pause, before pronouncing the word or part of the word that comes after the stop.

While what you read below is by no means exhaustive, it’s a good start – courtesy of both the United States Geological Survey and the National Park Service -  toward what you may see during your visit.

‘A‘ā and Pāhoehoe lava types, Hawai'i Volcanoes National Park / Rebecca Latson

‘A‘ā (ah ah): A Hawaiian term for a type of basaltic lava that is blocky and angular.

Basalt: A dark gray or black fine-grained igneous (volcanic) rock or very liquid lava containing 45 to 53 percent silica that is rich in iron and magnesium. Basalt is one of the most common rock types in the earth’s crust and entirely composes shield volcanoes.

Cinder Cone: The most common type of volcano in the world, and in the National Park System, a cinder cone is a conical hill, often steep, formed by accumulation of solidified fragments of lava falling around the vent of a single basaltic or andesitic eruption. The rock fragments, often called cinders or scoria, are glassy and contain numerous gas bubbles "frozen" into place as magma exploded into the air and then cooled quickly. Cinder cones range in size from tens to hundreds of meters tall.

Kīpuka (kee poo kah): Literally “islands within islands,” a kīpuka is an area of land surrounded by younger lava flows, in effect an "island" within a sea of lava.

Flying over a Kīpuka, Hawai'i Volcanoes National Park / Rebecca Latson

Lava Lake: Hike the Kīlauea Iki Trail and you will find yourself walking across the expanse of a solidified lava lake, once a pool of molten lava issuing forth in great amounts from a vent or crater.

Lava Tree: When lava flows around a tree trunk, it kills the living tree but leaves a hardened shape of the tree once there. Lava trees are good indicators of where an actual forest once stood.

Lava Tube: Underground passageways created by lava flows that stop or get diverted, leaving an empty cave. Thurston Lava Tube (Nāhuku) is an example.

Looking toward the entrance of the Thurston Lava Tube (Nāhuku), Hawai'i Volcanoes National Park / Rebecca Latson

The "Firehose," an active lava tube conduit that will someday become a lava cave after the lava stops flowing or is diverted, Hawai'i Volcanoes National Park / Rebecca Latson

Pāhoehoe (paw-hoey-hoey): A Hawaiian term for a type of basaltic lava that viscous and smooth or ropey.

Pele’s Hair: Thin glass fibers formed by gas during a volcanic eruption. When bubbles of gas near the surface of a lava flow burst, it can stretch the skin of the molten lava into long threads. Strands of Pele's hair may be up to a couple feet long, but only one micron (.001 mm) thick. Pele’s hair is fragile and can break into tiny pieces forming splinters that can get into your hands.

Pele’s Tears: These volcanic glass drops do indeed look like tears. They are created when airborn particles of lava cool and fuse into tear-shaped drops.

Petroglyph:  An image carved in stone. The Puʻuloa Petroglyphs are great examples and the trail to access these is found along the Chain of Craters Road.

Pit Crater: Depressions that form primarily as the earth fractures when a volcano shifts or expands. These are prevalent along the Chain of Craters Road.

Shield Volcano: A broad shield-shaped volcano that is built up by successive, very fluid basaltic or andesitic lava with a low silica content (the more silica in lava, the more explosive it becomes). Examples of shield volcanoes are Mauna Loa, Mauna Kea, and Kīlauea.

Steam vents and the Mauna Loa shield volcano, Hawai'i Volcanoes National Park / Rebecca Latson

Sea Arch: Drive to the end of Chain of Craters Road where you can view the Hōlei Sea Arch, the remnant of a sea cliff created where lava kept adding to the land, then eroded by the constant pounding and pulverizing of wind and ocean waves.

Skylight: An opening in the roof above a lava tube.

Steam Vent: As you walk along the trails near the park’s visitor center, you’ll notice holes in the ground from which issue warm steam. These steam vents occur when water seeps down to rocks heated by magma deep underground. Those hot rocks vaporize the water, returning it to the surface as steam.

Sulphur Bank: Something very similar to the steam vent are the sulphur banks (Ha'akulamanu), basically steam vents with both water steam and volcanic gases sulfur dioxide (SO2) and hydrogen sulfide (H2S), both of which have a struck match / rotten egg smell.

The sulphur banks seen at Ha'akulamanu, Hawai'i Volcanoes National Park / Rebecca Latson

Tree Mold: The opposite of lava trees, these are cavities or holes where trees stood in a lava flow. As with lava trees, the plant will burn up when the flow approaches. However, tree molds occur when the flow does not subside or deflate. By not subsiding, the flow does not expose the column of lava that makes up a lava tree.

You may hear Halema‘uma‘u crater and Kīlauea caldera, in addition to just the term Kīlauea volcano. Kīlauea caldera is the a large depression formed when the volcano first erupted, then collapsed. It’s a shield volcano that is believed to have formed around A.D. 1500. Halema‘uma‘u crater, located within Kīlauea caldera, is the volcano’s most active vent. Halema‘uma‘u crater is where you see most of the lava eruptions and lava fountains and lava pyrotechnics.

To read a far more detailed glossary of volcanic terms, here’s the USGS Volcano Hazards Program glossary and the NPS Glossary of Volcanic Terms.