• This 1982 photo provided by The National Park Service shows a park employee sitting on a rock in Calcite Lake at The Wind Cave National Park in the Black Hills of South Dakota. The underground lakes, which were discovered in the 1960s, aren't home to any animal life but prominent cave microbiologist Hazel Barton has discovered there is bacteria - albeit scant - in the lakes. Barton hopes to decipher how the bacteria survives and answer questions about how it interacted before multicellular organisms came along and perhaps find new sources of antibiotics. (The National Park Service via AP)

    Far below South Dakota, a cave holds pure, promising water

    WIND CAVE NATIONAL PARK, S.D. (AP) — Hundreds of feet beneath the Black Hills, a team of scientists and researchers snake through dark, narrow and silent corridors of ancient rock to reach their goal: what is thought to be some of the purest water on Earth.