Useful links and articles about the pros and cons of diving:

Benefits:
 

Population monitoring: http://onlinelibrary.wiley.com/doi/10.1111/j.1523-1739.2004.00015.x/abstract

Discovering species :http://www.mcsuk.org/what_we_do/Wildlife%20protection/Conservation%20in%20action/MCS%20Seasearch%20divers%20discover%20new%20sponge%20species

http://www.mcsuk.org/what_we_do/Wildlife%20protection/Your%20Seas%20Your%20Voice/Divers%20find%20the%20world's%20longest%20chalk%20reef%20off%20Norfolk

Expanded knowledge of marine life distribution: http://www.mcsuk.org/press/view/21

Money from the tourist industry used to fund conservation projects: http://www.sciencedirect.com/science/article/pii/S0025326X00000229

http://www.sciencedirect.com/science/article/pii/S0964569102000492

 

Costs:

Damaging coral reefs: http://www.dive.in/articles/a-scuba-divers-impact-on-a-coral-reef/
 

http://www.jstor.org/discover/10.2307/4314577?uid=3738032&uid=2134&uid=2&uid=70&uid=4&sid=21104060715513

http://www.sciencedirect.com/science/article/pii/S0006320701000854