The "Download Now" link directs you to the iTunes App Store, where you must continue the download process. You must have iTunes installed in order to open the link, and you must have an active iTunes account to download the application. This download may not be available in some countries.
From Chameleon (WA):
Dive Formulas provides all of the formulas used by the recreational diving community in one handy place. It allows you to enter the necessary details and calculates the appropriate result based on your input. It also shows you how it calculated the result, making it especially useful as a teaching aid for instructors and students alike.The following conversions are available:Partial Pressure of a Gas (Dalton's Law)Fraction of a Gas (Dalton's Law)Maximum Operating Depth (Dalton's Law)Absolute PressureEquivalent Air DepthOxygen Tolerance UnitsBoyle's LawCharles' LawAmontons' LawLifting CapacityGas Volume RequiredPressure Conversions