What is the largest volcano in the world?

The World’s Largest Volcano: It’s Not Always What You See

What is a volcano, anyway? Seems like a simple question, right? It’s basically just a spot where hot stuff from inside the Earth—we’re talking molten rock, or lava as it’s known when it hits the surface—finds its way out i. Over time, all that oozing and hardening creates the cone-shaped mountains we picture as volcanoes i. But try defining the largest volcano, and suddenly things get a whole lot murkier. Are we talking about how tall it is? How much ground it covers? Or maybe how much space it takes up underground? And what if most of it is underwater, hidden from view?

For years, there was really only one answer to the “world’s largest volcano” question: Mauna Loa in Hawaii ii. “Mauna Loa” means “Long Mountain” in Hawaiian, and trust me, it lives up to the name iii. This is what’s called a shield volcano, meaning it’s wide and gently sloping, like a warrior’s shield laid on the ground iii. In fact, it makes up more than half of the entire Island of Hawaiʻi iii!

Now, at 13,681 feet above sea level, Mauna Loa isn’t exactly small iii. But here’s the kicker: it goes down much further than it goes up iii. It plunges another 16,400 feet to the ocean floor iii. And get this: its sheer weight is so massive that it actually squishes the Earth’s crust down by another 5 miles iii! From its hidden base to its summit, Mauna Loa stretches over 30,000 feet—taller than Mount Everest iii. And if you could somehow gather all of Mauna Loa together, it would fill somewhere between 15,600 and 19,200 cubic miles iii. Plus, it’s a restless giant, having erupted dozens of times iii.

But hold on, the story doesn’t end there. Mauna Loa’s long-held title has been challenged, and ultimately, snatched away.

Tamu Massif: A Challenger Appears… Then Fades

Back in 2013, scientists started buzzing about Tamu Massif, a huge, dead volcano sitting way down under the Pacific Ocean iv. It’s about 1,000 miles east of Japan, and it’s enormous, covering an area roughly the size of New Mexico or Japan iv. For a while, everyone thought Tamu Massif was a single volcano, fed by one central source iv. That would have made it the biggest single volcano on the planet.

But like many things in science, the story got more complicated. Turns out, Tamu Massif isn’t one single volcano at all v. A later study in 2019 suggested that it was formed by seafloor spreading at a triple junction of mid-ocean ridges v. Basically, it’s a giant pile of oceanic crust, not a single volcanic vent v. Interesting, sure, but not quite the record-breaker we thought it was.

Pūhāhonu: The Real King

So, who is the current champ? Drumroll, please… It’s Pūhāhonu, another Hawaiian volcano vi! The name means “turtle rising for breath” in Hawaiian vi. You might also know it as Gardner Pinnacles. It’s way out in the Papahānaumokuākea Marine National Monument, a good 600 miles northwest of Honolulu vi.

What makes Pūhāhonu so mind-boggling is its sheer volume vi. Experts estimate it packs around 150,000 cubic kilometers of rock vi. That’s twice the size of Mauna Loa vi! The crazy part? You can barely see it vi. All that’s visible are a couple of tiny peaks sticking out of the water, a measly 170 feet high vi. The rest of this behemoth is hidden beneath the waves vi.

Over millions of years, Pūhāhonu’s massive weight has actually caused the Earth’s crust to sink vi. And get this: it started forming somewhere between 12.5 and 14.1 million years ago vi. Talk about ancient!

Other Volcanic Heavyweights

While Pūhāhonu, Mauna Loa, and Tamu Massif battle it out for the “largest” title, there are other volcanoes that deserve a shout-out for their extreme features.

• Olympus Mons: This Martian monster is the largest volcano in the entire solar system vii!
• Mauna Kea: Another Hawaiian giant, Mauna Kea is actually taller than Mauna Loa if you measure it from its base on the ocean floor to its peak viii.
• Ojos del Salado: Straddling the border between Chile and Argentina, this one’s the highest active volcano on Earth ix.

The Takeaway

The search for the world’s largest volcano is a fascinating reminder that our planet still holds plenty of secrets. While Mauna Loa wowed us for years, and Tamu Massif briefly teased us with its size, Pūhāhonu now wears the crown, thanks to its incredible volume. This hidden giant reminds us that there’s always more to discover, especially beneath the surface.