Penetration diving or no clear surface diving is a type of diving where the SCUBA diver enters a space from which there is no direct, purely vertical ascent to the safety of breathable air of the atmosphere at the surface. Several types of dive meet this condition: cave diving, wreck diving, ice diving or diving other man-made, underwater structures or enclosures.

The fact that the diver cannot immediately ascend to breathe from the atmosphere at the surface makes this type of diving much more risky than the usual types recreational diving or open-water diving.

It is essential that divers doing penetration dives are specially equipped and trained in technical diving techniques such as:

• using redundant diving cylinders
• using distance lines to guide the diver to the exit.
• using other breathing gases than air. Nitrox is used for shallow diving and Trimix for deeper dives.

External links

• GUE - Global Underwater Explorers (http://www.gue.com/)
• IANTD - International Association of Nitrox and Technical Divers (http://www.iantd.com/)
• NACD - National Association for Cave Diving (http://www.safecavediving.com/)
• NSS-CDS - National Speleological Society Cave Diving Section (http://www.nsscds.com/)
• WKPP Woodville Karst Plain Project (http://www.wkpp.org)