I could write for a long time about diving off Pinellas County (Clearwater), and it's neighboring counties, Pasco, and Hernando.
The Gulfcoast gets deep gradually; it's not like the Atlantic Coast of Florida. Pasco County especially has some incredible flats fishing because 23 miles off shore you are still in only 17 ft of water. Clearwater gets deeper a little quicker, and St. Pete quicker yet.
You asked about vis. Yes, it's good over here. I have many dive buddies who do mostly Florida east coast stuff (Atlantic) and they envy our vis. They contend frequently with 5 - 10 ft, whereas we have 30 - 40 quite often. Our vis can go downhill be algae growth, and tropical depressions or storms. A major blow can screw vis up for a while.
You asked about structure. You'd be diving primarily two kinds of structure: ledges and wrecks. The ledges/reefs we have here are not the tropical kind you see in the keys. You have to go a little south for that, although I have seen some impressive coral. I don't know how far offshore you would plan on going but if under 50 miles you'd be looking for little 2-3 foot breaks. This is from a spearfisherman, though. If your thing is photography, then you'll probably like the wrecks better, and there are plenty of them. Many are published numbers.
Hit the Mexican Pride wreck first in 130ft of water and you will be impressed at not only the structure, but the marine life. Last time I was on it I got to see herds of monster jewfish, American Red Snapper, mangos, cudas galore, amberjack city, gag grouper, the whole deal.
If depth of 100 - 140 don't bother you, the very best thing about living on Florida's Gulfcoast is your promixity to the fabled Florida Middle Grounds. Huge ledges, sometimes with a 30 - 50 ft break. I've got over 1000 numbers in the Florida Middle Grounds, and several spots that I take first timers because I know they will get slack jawed when they see it. Plan on a total trip of 220 miles, including the crusing around you'll do once in the Grounds. You'll be in he Grounds about 80 miles from Port coming out of Clearwater.
Oh, and the vis in the Middle Grounds...awesome! On bad days it's 30ft, but many times 100ft. Also, the water gets real blue out there, as you're well away from the inshore green water.
Does the diving get better further south? Keys? Guess it depends on your agenda. I am quite happy diving right here, and will leave the Florida Keys to all the tourists.
A good investment is a bathymetric program, BTW.
Hope this helps.
ScubaRon
