Aims and objectives of the book:To get acquainted with the introductory information about garnished mixtures for amateur diving . Understand how enriched mixtures can be useful in non-decompression dives. To get acquainted with various myths concerning diving on enriched mixtures . Compare profiles of decompression-free dives performed in air and on nitrox. Get initial information about the history of the development of enriched mixtures . Understand the nature of gases. Learn the basic properties of air and atmospheric gases that make up it. Get acquainted with the quantitative aspects of the behavior of gases (gas laws), understand the risk posed by nitrogen anaesthesia . Get initial information about the partial pressure of the gas, its value. and td.