Maui is the second-largest of the Hawaiian islands and owes its formation to past volcanic activity. The island is predominantly made up of two volcanoes, East Maui, also known as Haleakala, and West Maui, joined by a much lower area of land. As a result, most of the island’s landforms are volcanic.

Cinder Cones


Cinder cones dot the landscape in parts of the Haleakala National Park. The cones build up over time as ash and chunks of molten lava erupt under pressure from a volcanic vent. This material does not travel far from the vent and over time forms layers that lift the opening of the vent above the surrounding landscape. The U.S. Geological Survey estimates that the cones within Haleakala's crater date back around 800 years, but other cinder cones on the east and southwest coasts are more recent, dating from between 200 and 500 years ago. The cones on the floor of Haleakala fall into the wilderness area of Haleakala National Park and vary in color between red and brown.

Lava Flows

Maui also shows extensive evidence of past lava flows. The Hawaiian volcanoes are classified as shield volcanoes, formed from repeated eruptions of non-viscous, or “runny” lava. The lava spreads out from a central vent in all directions, creating the distinctive gently-sloping dome. Research undertaken by the U.S. Geological Survey found that the most recent lava flows took place between 900 and 4,000 years ago. Areas with lava deposits less than 1,500 years old exist in the Haleakala crater, in the northeast around Hana and on the southwest slope, where some flows occurred less than 500 years ago.



Like any small island, the coastline is one of Maui’s most prominent features. The often jagged shape is the result of its formation from lava flows meeting the surrounding ocean. When the hot lava met the cold water it cooled and hardened, creating the spiky headlands and narrow bays seen today. The coastline around Nahiku in northeast Maui exhibits numerous small bays with pocket beaches made up of boulders and smaller pebbles of basalt and shingle. The shape of volcanic flows under the ocean makes Maui’s northern coastline a favorite with surfers, who ride waves of up to 68 feet off Ke’anae Point.



Maui’s lava base provides the island with fertile soils, supporting a variety of specialized ecosystems with many unique species. Rainforest is dominant on the island’s windward slopes where the native koa and ohia trees form a closed canopy. However, this environmentally significant area is vulnerable to land erosion. Rooting and grazing by pigs and goats removes the vegetation holding the soil together, meaning that rainfall washes away the soil. In an effort to ameliorate the problem, Haleakala National Park and the East Maui Watershed Partnership have removed all pigs and goats from Haleakala’s upper slopes to protect the soil, the groundwater and the delicate ecosystem that depends on them.

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