For 100 years lava boiled in this crater-within-a-crater.

Halema'uma'u lies at the heart of Kilauea, an active volcano with a fiery reputation. From 1823 until 1924, Halema'uma'u contained a lava lake that fascinated visitors from around the world.

Today scientists believe that the top of the underground reservoir of hot molten rock that feeds the volcano lies about 3 Kilometer (2 miles) below Halema'uma'u. When pressure in the reservoir builds, lava may erupt here, or at vents or fissures along the sides of the volcano.

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