Their fate remained unknown for seven and a half years .
Their attempts to escape the wrecked submarine using IDA - 51 apparatuses failed , and all 68 officers and men of S - 80 were lost .
officers ' fate remained unknown for seven and a half years .
Their attempts to escape the wrecked submarine using IDA - 51 apparatuses failed , and all 68 officers and men of S - 80 were lost .