your id numbers have to be on the tank and the flag,, and youll find more in rockey deep areas,, i havent tried snorkeling for them and i dont think i would somegood hunting areas that i go to are,, cape ann,, gloucester,rockport,, Old garden beach,, if you want more info send me a messege and ill give you more info,, also lemme know what youre closer to and how far youd travel!.... Dana