Certain areas of the world provide spectacular dives at depths deeper than 39m/130 feet but you will not have access (or very limited access) to helium. The TDI Extended Range course teaches you the proper techniques for utilizing compressed air as a breathing gas and with a maximum depth of 55m/180 feet you won't have to miss those dives. The Extended Range course will cover topics and skills such as " Equipment requirements and configuration " Decompression options " Use of surface marker buoys " Buddy rescue " Narcosis checks and management Materials for this course include the TDI Extended Range Diving Manual and the US Navy or Buhlmann Air Decompression Tables (made of vinyl for easy in-water use and storage)