NAS is the Nautical Archeology Society which is an NGO based out of Portsmouth England. They are focused on Maritime Heritage and Archeology
They can be found here :
http://www.nasportsmouth.org.uk/
In Canada (and in many othere countries) they are the de facto training standard for underwater archeology training.
The first course NAS 1 has no prerequisits other than OW diver. It covers basic archeological principles and how to survey an underwater site without any intrusive efforts. Having this course would allow a diver to assist in the archeological survey of a site.
Taking this course also allows the diver to hum the theme to Indiana Jones and the Raiders of the Lost Ark while diving....
Further courses increase the knowledge and ability of the NAS Diver up to the last course NAS 4 which would certify them to be able to act as the site supervisor under a director.
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Ontario Diver
"It's Cold, It's Murky. Lots of Wrecks, 18 Species of fish (all various shades of brown and green) but the best beer in the world"