Hawaii’s Big Island is the Island of Hawaiʻi, the largest and youngest island in the Hawaiian chain. At 4,028 square miles, it’s bigger than all the other Hawaiian islands combined and still growing thanks to active volcanic eruptions. It sits at the southeastern end of the archipelago and is the island that gives the entire state its name, which is why locals call it “the Big Island” to avoid confusion.
Size and Location
The Hawaiian archipelago stretches 1,523 miles across the Pacific, making it the world’s longest island chain. It includes 132 islands, but only eight are considered main islands. The Big Island dwarfs them all. The total land area of the entire state is about 6,423 square miles, meaning this single island accounts for nearly two-thirds of it. For mainland comparison, the Big Island is roughly the size of Connecticut.
Despite its size, the Big Island is not the most populated Hawaiian island. That distinction belongs to Oʻahu, home to Honolulu. The Big Island’s population is spread between two main towns on opposite coasts: Hilo on the rainy east side and Kailua-Kona on the dry west side, with smaller communities scattered in between.
Five Volcanoes Built the Island
The Big Island formed from five separate shield volcanoes that erupted over the same hotspot in the Earth’s mantle, eventually merging into one massive landmass. Two of them are still very much active. Kīlauea, one of the most frequently erupting volcanoes on Earth, has been erupting episodically since December 2024 from vents inside its summit crater. Mauna Loa, the world’s largest active volcano by volume, last erupted in late 2022 after a 38-year quiet period.
The other three volcanoes are in various stages of retirement. Hualālai, on the western coast above Kona, last erupted in 1801 and is still considered active. Kohala, at the island’s northern tip, is the oldest of the five and has been extinct for roughly 60,000 years. Then there’s Lōʻihi, an undersea volcano growing about 970 meters below the ocean surface off the island’s southeastern shore. It may eventually break the surface and become the newest addition to the chain, though that’s likely tens of thousands of years away.
Mauna Kea: Tallest Mountain on Earth (By One Measure)
Mauna Kea’s summit sits 13,803 feet above sea level, making it the highest point in Hawaii. But the more striking number is what lies beneath the waterline. Measured from its base on the ocean floor, Mauna Kea rises roughly 33,000 feet, which leads some authorities to call it the tallest mountain in the world from base to peak. Mount Everest is higher above sea level, but Everest sits on an already elevated plateau rather than rising from a deep ocean trench.
That extreme height is also what makes Mauna Kea one of the premier astronomy sites on the planet. Thirteen telescopes operated by astronomers from eleven countries sit near its summit, forming the world’s largest astronomical observatory complex. The summit rises above 40 percent of Earth’s atmosphere, and a persistent cloud layer about 2,000 feet below the peak acts as a natural barrier, keeping moist, polluted air from reaching the telescopes. The result is some of the driest, clearest, darkest skies available to science anywhere on Earth.
A Continent’s Worth of Climate in One Island
The Big Island contains four of the five major climate classifications used by scientists to categorize weather patterns worldwide. Tropical rainforest conditions line the windward (eastern) coast, arid and semi-arid zones stretch along parts of the leeward (western) coast, temperate climates exist at middle elevations, and polar-like conditions persist at the summits of Mauna Kea and Mauna Loa. You can drive from a lush rainforest to a barren alpine landscape in under two hours.
The rainfall differences are staggering. Hilo, on the eastern coast, averages well over 100 inches of rain per year, with some years recording more than 200 inches. Meanwhile, the Kona coast on the west side of the island gets as little as 20 to 38 inches annually, depending on elevation. The mountain slopes on the windward side can exceed 300 inches per year, making parts of the Big Island among the wettest places on Earth. The summits of Mauna Kea and Mauna Loa, paradoxically, are near-desert environments receiving 20 inches or less.
This happens because trade winds blow moist Pacific air into the eastern flanks of the mountains, forcing it upward where it cools and dumps rain. By the time air crosses over to the western side, most of the moisture is gone. That rain shadow effect creates two fundamentally different worlds on the same island.
Kona Coffee and Agriculture
The Big Island’s western slopes are home to the only commercially grown coffee in the United States. The Kona Coffee Belt occupies a narrow strip between 700 and 2,000 feet in elevation along the slopes of Hualālai and Mauna Loa. The volcanic soil there is exceptionally young, rich in organic matter, and full of crumbled lava rock that provides the sharp drainage coffee plants need. Morning sun, afternoon cloud cover, and mild temperatures at that elevation create ideal growing conditions.
Beyond coffee, the Big Island produces macadamia nuts, tropical fruits, cattle (the Parker Ranch in Waimea is one of the largest ranches in the United States), and a growing variety of specialty crops. The island’s diverse microclimates allow farmers to grow everything from vanilla to mushrooms to cacao.
Cultural and Historical Significance
The Big Island holds deep significance in Hawaiian history. It was the birthplace and power base of Kamehameha I, the ruler who unified the Hawaiian Islands into a single kingdom in the late 1700s. After consolidating his rule, Kamehameha moved his capital back to Kona in 1813, settling at Kamakahonu on the north end of Kailua Bay. His compound there included ʻAhuʻena Heiau, a restored temple where he held private councils with his highest advisors and his son and heir, Liholiho. The site, now a National Historic Landmark, sits adjacent to the modern King Kamehameha hotel in Kailua-Kona.
Hawaiʻi Volcanoes National Park, encompassing Kīlauea and a portion of Mauna Loa, is both a UNESCO World Heritage Site and a place of ongoing cultural importance. In Hawaiian tradition, the volcanoes are the domain of Pele, the goddess of fire. The park draws visitors for its active lava flows, vast crater landscapes, lava tubes, and petroglyphs carved into hardened flows centuries ago.
Two Coasts, Two Personalities
Hilo and Kona function as the island’s two centers, and they feel like different places entirely. Hilo is quieter, greener, and more affordable, with a small-town downtown, farmers’ markets, and waterfalls within a short drive. It’s the county seat and home to the University of Hawaiʻi at Hilo. Rain is a near-daily occurrence, which keeps the landscape impossibly green but also keeps mass tourism at bay.
Kailua-Kona, on the dry western coast, is the island’s tourism hub. Resort areas stretch along the Kohala Coast to the north, where white sand beaches and calm waters attract visitors year-round. The Kona side is also where the Ironman World Championship triathlon takes place each October, one of the island’s signature international events. Between the two coasts, the Saddle Road crosses the plateau between Mauna Kea and Mauna Loa, offering access to the island’s high-altitude interior and the observatories above.