I hear John Pennekamp National Park in Key Largo, Florida is the best in the continental US...Hawaii no doubt is the best for U.S. in it's entirety.
My mother-in-law lives in Ester, FL and we're taking a 2.5 hour trip to Key Largo since there are somewhat close. Key Largo and Key Biscayne are the closest keys. Biscayne National Park has a massive "man" induced/artificial reef area...
Christ of the Abyss is in John Pennekamp National Park. Look it up on Youtube.com
I'll let you all know how it is in a couple weeks.
Info:
Established in 1963, John Pennekamp Coral Reef State Park was the first undersea park created in the United States. The park, combined with the adjacent Florida Keys National Marine Sanctuary, encompasses 178 nautical square miles of coral reefs, seagrass beds and mangrove swamps. These areas were established to protect and preserve the only living coral reef in the continental United States. Coral Reef State Park now enjoys over a million visitors per year from around the world.
More Info:
What makes the coral reefs of the Florida Keys so special? Well, for starters, the Florida Keys Reef Tract is the only living coral barrier reef in North America, and is the 3rd largest coral barrier reef in the world (after the Great Barrier Reef in Australia and the Meso-American Reef in Belieze). The reef runs roughly 221 miles down the south-eastern coast of Florida, paralleling the Florida Keys from Key Biscayne off Miami down to the Dry Tortugas, 70 miles west of Key West, from 1 mile to 8 miles offshore. The proximity of the reef (just a half-hour boat ride from land); the warm, clear water from the Gulf Stream just offshore; and the fantastic richness of life found here makes the reefs of the Florida Keys one of the most uniquely beautiful and accessible wild areas in the country.
Unfortunately, many visitors to the Keys come down with no real understanding of what a coral reef is! REEF is a general term usually referring to a relatively shallow area of hard structure that tends to attract animals. ALGAE REEFS are found in many areas in the South Pacific, where the primary structure is calcareous algae; ROCK REEFS are common in the Northeastern U.S., where accumulations of granite or other rocky outcroppings have gathered a variety of biofouling organisms and fish to form an active hardbottom community; in many areas, people have even sunk concrete structures, old ships, or railroad cars to form ARTIFICIAL REEFS, which are rapidly colonized by various types of fish and fouling organisms (ex., sponges, tube worms, and hard and soft corals).
CORAL REEFS are special because of the community of organisms that build the reef, the HARD and SOFT CORALS. Corals are animals in the Phylum Cnidaria (the group of animals that includes jellyfish and sea anemeones), Class Anthozoa. Corals are found in a variety of forms, from the hard branches of Elkhorn Coral to the soft leaf-like structures of Sea Fans. Corals can generally be divided into SOFT CORALS (Subclass Octocorallia), which have a soft, flexible skeleton of protein (similar to what makes up human fingernails or hair); and HARD CORALS (Subclass Zoantharia, Order Scleractinia), which form a hard exoskeleton of secreted calcium carbonate (limestone). Since the hard corals have a skeleton that is literally rock, it is their growth that really forms the structure of the reef. Each coral head is really a colony of thousands of individual animals called CORAL POLYPS, which look something like upside-down jellyfish.
Wow my summation sounds pretty close...