Is Horseshoe Lagoon on Big Pine Key really a decent dive site??

I have seen the following comment on a couple of websites: does anyone know if this site is really worth diving on Big Pine Key?? I searched SB and saw no mention of it from anyone. Thanks

Immediately after crossing the Bahia Honda Bridge (MM 36), turn off to the right at MM 35-B and park in the gravel parking lot. Walk towards the water and you will find a deep lagoon referred to as the “Horseshoe.” This off-the-beaten path dive and snorkel site is actually an old quarry where coral was dug out to use in the construction of the Bahia Honda Bridge. This is a great place to snorkel and SCUBA dive- especially on windy days, as it offers protection from choppy seas, and the water is always clear. An abundance of sea life, including parrotfish, barracuda, snapper, and small tropical fish can be found around the coral base of the Horseshoe, as well as lurking in the dark waters of the quarry’s center.

From The Yak - life, fish & kayaks from the Florida Keys

I've heard the legend of it. It sounds like a great rough-seas diving alternative. It sounds like a great field trip to me!

I did some research on the web and found this. I think it is the dive site. There are a couple of vehicles parked on the gravel in the google earth image. It is about 150 yards from the parking area to the lagoon. I will be real interested in hearing from anyone checking out this site. I am planning a Keys trip in June.

I'll be going down in July & would be interested in hearing any news about this as well.

After delaying plans on a larger dive trip I may end up in the keys in a couple
weeks, I will definitely check this out !

Herbdb..that's a nice shot of the "Horseshoe" It's 30'deep in the center, just mud....off the center the remnants of the Ambulance attract a large school of "LookDowns" who come around to see just what you are doing.. around the edges (east side) will be crevices full of tropicals and game fish. The viz is mostly low (10-15') It does make for an interesting night dive.
It's a haul, carrying you gear to the edge..just wear it to the site..do use a flag (local law) and keep in mind, it's best to have a group..with several cars around...you wont be able to see your car/truck from the site (a little sign warns of high crime).. stop by Underseas in BigPine..right by the TomThumb...I can draw you a little overview map..

Scubamama, thanks for the additional information. Can you tell me what the path to the water is like? I have a four wheel folding trolley that we use to move crates and dogs at dog shows. It has fat tires and is designed to work on grass. Would the surface be hard enough to use the cart?

We travel primarily by motorhome so bringing the trolley is no big deal if it would work. I lost three days diving during my last trip to the keys for weather? This may be just the ticket when the weather is kicking up.

The lagoon is surrounded by some pretty shallow water. Have you ever seen boats in the lagoon?

Herbdb. You got the best cart for haulin'......the path is hard packed..wont be a problem. Very few boats come thru...shoals on both sides of the opening.

I have been diving in "Long Key Quarry" between Duck Key and Marathon... just past the dolphin research center. There are several "quarries" up and down the Keys along US1. I used it when we were blown out and I had to finish a class as the students were headed to the Caribbean the next weekend. I imagine the conditions are not that different than the Horseshoe in the op. The water is kind of a eerie black/gold, but there is some vis... maybe around 10 feet or so. In the winter it is very cold being on the bay side. The middle is muck and mud, but on the Long Key hole some dive shops have sunk an old wooden billboard to use as a platform. There are some tropicals and small 'cudas hanging around the stone walls, maybe and mang here and there. To be honest, every time I was in there I keep wondering about crocodiles. Ha! I don't even know if they are around or not, but it looked like primo croc territory to me.

Is it worth it on a nasty day as a fun dive? Simply stated- nope. If those old rock holes were worth it people would be in them all the time and no secret to anyone here.

I’ve dove that quarry on bigpine a few times with the same thoughts, dark and cold! There is another quarry in Bahia Honda State Park that I have been fishing before... that one always looks alot clearer but unfortunately, the posted signs outlaw snorkeling and diving...