Rick Murchison:Just went back & reviewed the SSI standards... the 40' is a "hard floor" for 10-11 year olds; the 60' is not a standard but rather falls as a "recommendation" for the 12 & over Junior OW.
Rick
My reply was meant to make clarify standard with respect to PADI. The 70' depth allows for a "deep" dive (below 60') so that a 12-14 year old can get a Junior Advanced Open Water certification.