The term bog bodies are human burials, some likely sacrificed, placed within peat bogs of Denmark, Germany, Holland, Britain, and Ireland and naturally mummified. The highly acidic peat acts as a remarkable preservative, leaving the clothing and skin intact, and creating poignant and memorable images of people of the past.
The reason that bogs permit a high level of preservation is because they are both acidic and anaerobic (oxygen-poor). When a body is thrown into a bog, the cold water will hinder putrefaction and insect activity. Sphagnum mosses and the presence of tannin add to the preservation by having anti-bacterial properties.