In June of 1992, I did 13 dives in 3 days at a number of sites in the Florida Keys. These dives were reefs or wrecks off of Islamorada and Plantation Key.
Other than 1 dive site (Davis Ledge), there were no moorings on the reef dive sites off of Islamorada and Plantation Key. The dive boat (as well as others that I saw) all anchored, sometimes directly on the coral. Even the times that the anchor was dropped in the sand, the chain rode often would be hitting the coral. During those dives, I saw much damage apparently caused by anchors and chain rodes. There were numerous corals with gouges, cuts, deep abrasions, and other scars.
The boat also used concrete cylinders hanging on both sides of the boat as safety stop lines. On one particular dive, the crew let out too much line. The starboard hang line with the concrete cylinder was pounding a brain coral with each rock of the boat.
Each dive except for the 3 wreck dives, I brought up 1 to 3 cans (more than half were Budweiser). I also found 2 cans and 1 bottle that were encrusted over which I left.
On more than 1/2 of the dives, I brought up plastics of some type, most commonly plastic trash bags and baggies and pieces of plastic cups.
Davis Ledge is a semi-circular ledge roughly 25 deep in the sand with a coral ledge ranging from 3 - 8 feet high. I dove it twice; during the day dive, there were no fewer than 50 divers on this 1/4 mile long ledge, plus an assortment of cans and plastics. Also, there was considerable coral damage and sand covering on the top of the ledge. Clearly, some of the damage could have been caused by the shallow depth and sand at the bottom of the ledge. However, the sheer number of divers must be contributing. People were literally climbing over the ledge. I wouldn't be surprised to hear that dive operators take inexperienced divers to this site because it is shallow and there's no need to navigate (you just follow along the ledge in one direction, then turn around and come back along the ledge).
The state of the coral and other sessile invertebrates was very poor. I saw few soft corals or large sponges. There was more algae and sand on the hard corals than what I have seen before in other areas of the Caribbean. The fish population looked reasonably healthy -- not overly abundant, but certainly not sparse. Interestingly, the healthiest 2 sites were the two wrecks, the Eagle and the Duane. Both sites had good healthy growth over the wrecks, plus very abundant fish life. The current on both (especially the Duane) was substantial, and both were relatively deep (115 and 130 feet respectively).
I worry that the Florida Keys will be a lost cause. They certainly won't be there for the next generation, and may be gone even earlier if we continue to abuse them like this. It's ironic that the United States is on the verge of destroying its only coral reef system (in the continental U.S. that is) while some so-called "third-world" countries of the Pacific and Caribbean have recognized the need to preserve them.