In late October and early November, the waters in the Gulf of Mexico clear up with visibility in some areas up to 80 feet. That makes for great scuba diving and spearfishing.  
Most folks know about the stellar conditions in the Florida Keys and on the state’s Atlantic Coast, but the Gulf of Mexico has its share of wrecks, artificial reefs and natural limestone outcroppings, often referred to as "hard bottom," that are well worth a visit. …