http://www.underwaterdiscovery.org
2. Global Underwater Explorers
http://www.gue.com
3. CMAS
http://www.cmas.org
4. AAUS
http://www.ucsd.edu
5. Divers Alert Network
http://www.diversalertnetwork.org
6. NASDS
http://www.nasds.com
7. PADI
http://www.padi.com
8. Canadian Diving Group
http://www.divinggroup.com
9. NAUI Online
http://www.naui.org
10. IDEA
http://www.idea-scubadiving.com