The world's biggest magma chamber is located beneath the Tamu Massif, an extinct underwater volcano in the northwest Pacific Ocean.

It's important to note that while it's the largest known magma chamber, its size is still a subject of debate among scientists. Some studies suggest it could be as large as 120,000 cubic miles (500,000 cubic kilometers), while others estimate it to be significantly smaller.

However, even the smaller estimations make it one of the largest magma chambers ever discovered, exceeding the size of many active volcanoes on land.