What is the Open age group in diving ?
Such situations would include :- Decompression diving ( where the absorption of nitrogen gas in the diver 's body tissues precludes a safe and direct ascent without decompression stops ) - Cave , ice or wreck diving ( where penetration inside the target venue ( in a cave or wreck , or under sheet ice ) precludes a direct ascent , because a horizontal path must first occur back to the point of penetration ) .