http://www.aqualung.com/ - snorkeling and SCUBA diving equipment.

http://www.deeperblue.net/ - information source for the sport of freediving and snorkeling.

http://www.iafdusa.com/ - the International Association of Free Divers USA's home page

http://www.diversdiscount.com/ - SCUBA diving equipment with huge savings at divers discount

http://www.seflin.org/snorkel/ - destination guide for snorkeling hotspots.