Scientists reveal a colossal ocean 700km beneath Earth's surface, challenging our understanding of water origins. Ringwoodite, a mineral acting like a "sponge," holds this vast reservoir. Seismic analysis unveiled its presence, suggesting Earth's water may originate internally, not from comets. This discovery holds profound implications for Earth's water cycle and ecosystem sustainability.Scientists reveal a colossal ocean 700km beneath Earth's surface, challenging our understanding of water origins. Ringwoodite, a mineral acting like a "sponge," holds this vast reservoir. Seismic analysis unveiled its presence, suggesting Earth's water may originate internally, not from comets. This discovery holds profound implications for Earth's water cycle and ecosystem sustainability.