Miami Diving: A National Park That Is 95 Per Cent Water, and a Federal Box That Bans Spearguns

Most Miami diving happens inside a national park that is 95 per cent water

The boat ride out of Miami does not end at a dive site so much as at a park boundary. Biscayne National Park begins just south of Key Biscayne and covers roughly 172,971 acres, about 69,998 hectares. Of that, only 9,075 acres is dry, and the Park Service states flatly that the park is 95 per cent water.

What sits under the surface is the top end of a single long structure. The park protects the northern extent of the Florida Reef, a coral barrier tract the Park Service measures at about 275 kilometres, or 170 miles. Inside the boundary are more than 40 keys and 4,825 acres of mostly undeveloped mangrove shoreline. Elliott Key is the largest island in the park, and a track called Spite Highway still runs roughly six miles down the middle of it.

The park calls itself the largest marine park in the national park system, and describes its reefs as “the only continental subtropical coral reef and marine environment in the United States”. Both claims come from its own foundation document rather than from an independent ranking. Read them as the agency’s framing of what it manages.

Access is the practical catch. The foundation document says the primary means of reaching park waters is “by private, partner, or commercial permit-holding operators”, which in plain terms means a boat. Park headquarters sits on the mainland at Convoy Point, 9700 SW 328th Street in Homestead, well south of the hotel strip. Nobody swims to this reef from South Beach.

The founding law of Biscayne National Park keeps its reefs open to fishing

Divers arriving from the Keys often expect a no-take zone and find anglers instead. The reason is statutory and it is old. Section 4 of Public Law 90-606, signed on 18 October 1968, established Biscayne National Monument and provided that waters within it “shall continue to be open to fishing in conformity with the laws of the State of Florida except as the Secretary [of the Interior] … fishing is prohibited, limited or otherwise regulated in the interest of sound conservation”.

That language survived the upgrade. On 28 June 1980, Public Law 96-287 turned the monument into a park and added land north of Boca Chita Key, and section 103(a) repeated much the same sentence about fishing. Congress wrote the rod into the deed. Any restriction since has had to be argued against that starting point.

The argument came to a head in 2015. A final general management plan, released on 5 June 2015, proposed a no-fishing marine reserve zone of 10,502 acres, about 6 per cent of park waters, on the grounds that a marine reserve is one of the most effective ways to let a reef recover.

It never opened. In February 2020 the Florida Fish and Wildlife Conservation Commission approved a fisheries management plan for the park with no reserve in it, substituting five Coral Reef Protection Areas: Fowey Rocks Lighthouse, Alina’s Reef, Marker 3 Reef, Lob120 Reef and Ball Buoy. Inside those five, all traps and all lobster harvest are prohibited. Hook and line fishing continues.

The rest of the rulebook is state law under chapter 68B-7 of the Florida Administrative Code, in force from 1 July 2020 with updates on 1 April 2023 and 1 March 2026. Nine species carry higher minimum sizes inside the park than outside it, and a 10-fish aggregate bag covers drums, flounder, grouper, jacks, porgies and snapper. Lobster harvest stops entirely in the Biscayne Bay and Card Sound Lobster Sanctuary, from the shore out to the barrier islands.

The Maritime Heritage Trail is six sites, and the park publishes the depth of every buoy

Wreck diving here is shallow, marked and documented to a degree that is unusual. The park has mapped six sites into a Maritime Heritage Trail, produced brochures for them and installed mooring buoys, and it publishes the coordinates and depth of each individual buoy. Use of a buoy is limited to four hours by any one boat.

Sorted by depth, the trail runs from snorkel to scuba. The Mandalay, a steel-hulled schooner lost in 1966 and known as the red carpet ship of the windjammer fleet, sits under four buoys reading 8 to 11 feet. Next up is the Arratoon Apcar, aground in 1878 near the men who were then building Fowey Rocks Lighthouse, at 11 to 18. Deeper again come the Erl King of 1891 at 15 to 20 feet, the Alicia of 1905 at 16 to 20, and the Lugano of 1913 at 18 to 22.

Two of them carry a story worth knowing before you get wet. The Alicia went down loaded with silks, silverware and fine household goods, and the salvage disputes that followed, in the park service’s own words, “led to a permanent rewriting of U.S. salvage laws”. The Lugano had been the largest vessel ever wrecked in the Florida Keys. An unnamed nineteenth-century wooden sailing vessel, marked only by its ballast stones, lies under two buoys at 10 and 11 feet.

The seventh feature on the trail is not a wreck at all. Fowey Rocks Lighthouse was constructed between 1875 and 1878, first lit in 1878, stands 130 feet above the water and is nicknamed the Eye of Miami. Nine mooring buoys ring its base at 8 to 30 feet, with a tenth at 56 feet, and the Coast Guard still maintains the light. The tower itself is closed, and the park’s foundation document estimates it will reach catastrophic impairment within 25 years.

Six is not the whole inventory. The same document counts “more than 100 submerged archeological sites in the park”, including wrecks, navigational aids and loose artifacts, most of them unbuoyed and unmarked. Our wreck diving guide covers coasts where the shipping did the same work.

Two Miami wrecks with opposite rules: HMS Fowey and the Half Moon

One wreck here is older than the United States and you may not go near it. HMS Fowey, a fifth-rate Royal Navy frigate, struck a reef and sank on 27 June 1748 at what is now called the Legare Anchorage, east of Elliott Key. Restrictions on in-water activity have stood there since about the time of Hurricane Andrew in 1992. Swimming, snorkelling, diving and anchoring are all prohibited inside the closed area.

Her legal status is stranger than her depth. Britain never relinquished title, and the park announced an agreement with the United Kingdom in 2013 recognising British ownership while the National Park Service manages the site, under its own policies, the Sunken Military Craft Act of 2004 and the UNESCO underwater heritage framework. The park’s own inventory of administrative commitments dates the memorandum 13 August 2015, so the two records differ on which signature counts.

Protection kept tightening. A major in-situ stabilisation project was carried out on the wreck in 2014, and on 21 February 2023 the state wildlife commission banned recreational and commercial traps across the Legare Anchorage site, roughly 1.2 square miles. Trawling was already out. The foundation document explains the vigilance in one sentence: the park “suffers from one of the highest number of incidents of vandalism, especially relating to looting of shipwrecks, within the national park system”.

Now the opposite case. Just outside Bear Cut, between Virginia Key and Key Biscayne, lies the Half Moon, a 366-ton two-masted steel schooner-yacht built in Germany in 1908 for Count Bohlen und Halbach and originally named Germania. Seized as a prize of war in 1914 and taken to New York, she ended her working life in Miami as a floating saloon and sank in the early 1930s. The Park Service dates the loss to a storm in 1930 and gives her as 155 feet by 40.

She is Florida’s seventh Underwater Archaeological Preserve, and the state invites people onto her. The wreck lies in 8 to 10 feet of water, with structure three to four feet below the surface, which makes her a snorkel as much as a dive. Miami-Dade’s artificial reef catalogue files the same site as a 154-foot steel sailing yacht in 10 feet. One is a grave. The other is a swim.

The speargun ban off Key Biscayne has its corners in the Code of Federal Regulations

North of the park boundary, one stretch of water off Key Biscayne is governed by a federal fishery rule rather than by park regulation, and divers regularly miss it. Section 622.182 of title 50 of the Code of Federal Regulations lists fifty-one special management zones in the South Atlantic. Number twenty-one on that list is named Key Biscayne/Artificial Reef H.

The rule draws it as a rectangle, corner by corner. It is “bounded on the north by 25°42.82′ N. lat.; on the south by 25°41.32′ N. lat.; on the east by 80°04.22′ W. long.; and on the west by 80°05.53′ W. long.” That is one and a half minutes of latitude from top to bottom, a box you can cross on one tank of air.

Two restrictions bite inside it. Table 2 of the section says that in zones (a)(1)(xix) and (a)(1)(xxi), “Use of spearfishing gear is prohibited”, and a separate line bars a sea bass pot or bottom longline across all fifty-one. Of the fifty-one zones the section lists, exactly two carry that speargun ban, and both of them are off Florida: the Ft. Pierce Inshore Reef and this one.

Miami-Dade County repeats the rule in plainer words in its own reef catalogue, where the whole site is headed Key Biscayne SMZ and annotated to say that spear guns, long lines and fish traps are prohibited. Note the mismatch: the county writes fish traps, the federal text says sea bass pot. If you fish as well as dive, read the federal wording rather than the summary.

The county also marked the box physically. In June 1997 it dropped two structures named SMZ Buoy Reef NW and SMZ Buoy Reef SW, ten and eleven modules apiece with 550 tons of limestone boulders each, in 38 feet of water. Their published coordinates land on the northwest and southwest corners of the federal rectangle. Leave the gun on the boat and take the action camera instead.

A Boeing 727, three tugs and a 215-foot barge went down off Key Biscayne

Inside and around that box lies a long run of deliberately sunk steel, put there on purpose and written down. Miami-Dade County started its artificial reef programme in 1981 and now manages 11 inshore and 17 offshore sites, into which it records placing nearly 50 large vessels, two retired oil production platforms, thousands of tons of cast concrete and limestone, and surplus United States Army tanks.

The Key Biscayne site predates the programme itself. A 120-foot steel ship named Biscayne went down in December 1974 in 60 feet. The Orion, a 118-foot steel tug, followed in December 1981 in 88 feet, and the 200-foot Lakeland in June 1982 in 135. By January 1985 the 220-foot Proteus was on the bottom at 72 feet.

Then came the run of tugs that most Miami boats still dive. The Rio Miami, 105 feet, went in during November 1989 at 67 feet, and the county credits her 30 feet of relief, a tall profile for a 105-foot hull. Belzona I followed in May 1990 at 68 feet, Belzona II in February 1991 at 60, and Belzona III in June 1991 at 65. The 215-foot Belzona Barge settled in 40 feet in August 1991, which puts it well inside a first dive of the day.

An aircraft is on this list too, and the county files it like any other object. Spirit of Miami, a 727 jet, was deployed in September 1993 in 115 feet with 15 feet of relief. Nearby, the 235-foot Sheri-Lyn lies in two pieces at 100 feet, bow and stern sunk separately in June 1987. Two M60 army tanks went down further north in June 1994, in 47 and 49 feet.

Three of the hulls arrived by way of the courts. In July 2001 the county sank the Etoile de Mer, the Miguana and the Brandy Wine, all three recorded in the catalogue as seized by US Customs, at 131, 138 and 145 feet. Plenty of the list is far beyond recreational reach: the Davey Hurst sits at 265 feet, the Tenneco oil platforms at 105, 110 and 185. The newest entry is not steel at all, but 22 concrete cars placed off South Beach in October 2025 in 22 feet.

Neptune Memorial Reef is a cemetery, and the county files it at 43 to 45 feet

Somewhere in that same rectangle, divers swim through a graveyard. The Neptune Memorial Reef is a permitted artificial reef built as an interpretation of the lost city of Atlantis, into whose concrete features cremated remains are set. Its operators place it 3.25 miles east of Key Biscayne. It is a cemetery that people book as a dive.

The county files it like any other deployment, and the numbers are more precise than the marketing. Phase I, listed as concrete prefabricated pieces, went in during October 2007 at 45 feet with 20 feet of relief. A second phase followed in August 2018 at 43 feet with 13 feet of relief. Both are recorded at 25°42.035′ N, 80°05.398′ W.

That position matters for more than navigation. It falls inside the Key Biscayne special management zone, and the county files the memorial under exactly that heading, which means the federal speargun ban runs over the graves as well as over the tugs. Depth figures quoted elsewhere for the site, usually 40 feet, do not match the county record. Where the two differ, the county catalogue is the one with a deployment date attached.

Seventeen months of dredging at PortMiami, and the argument over what it killed

Ask about the state of the reef here and the conversation turns, fast, to a shipping channel. Widening the entrance at the Port of Miami ran, in the words of the study that measured it, “during a 17-month period between November 20, 2013, and March 16, 2015”, and moved a reported 4.39 million cubic metres of material. Three peer-reviewed papers have since tried to price the damage. They do not agree.

Miller and colleagues, publishing in PeerJ in 2016, went back in December 2015 and sampled at 100, 200, 300, 500 and 700 metres from the channel. Mean sediment depth at the reference location was 0.3 cm against 3.0 cm at 200 metres, ten times higher. Complete colony mortality hit 17 of 55 channel-side colonies, 31 per cent, against 6 of 58 at reference sites. Their sharpest finding was about the monitoring: effects reached 700 metres while the project’s own programme looked out to 50.

The counter-case is just as quantified. Gintert and colleagues, in Environmental Monitoring and Assessment in 2019, compared measured mortality at 30 sites across Miami-Dade County against three predictive scenarios. Species-specific disease susceptibility determined 93.3 per cent of the mortality, they found, while dredging stress predicted it 6.7 per cent of the time.

Their headline figure is that climate-driven disease was “more than an order of magnitude (14x) more deadly” than the dredge. One caveat belongs next to it. Several of the authors worked for the consultancy running the port’s compliance monitoring and one for the county environmental department, which the paper states in its own author list.

Then the question reopened from an unexpected direction. Dobbelaere and colleagues, writing in Marine Pollution Bulletin in 2024 from UCLouvain with co-authors at Louisiana State, NOAA and the Florida wildlife commission, note that stony coral tissue loss disease “reportedly initiated in September 2014 at a reef site off Virginia Key” during the dredging. Their ocean model found the site could have been reached by fine sediments from the work, “especially those involving non-conventional rock-chopping techniques”, and ruled wastewater unlikely.

For a visiting diver the practical reading is narrow. The sites closest to Government Cut carry the longest paper trail of damage in Florida, the disease and the dredge overlapped in time and place, and no published study has separated them to everyone’s satisfaction. Expect low stony coral cover and a lot of fish. The question is not settled.

The corals in Miami’s shipping channel did not die the way the offshore reefs did

One result from the same water runs against every expectation. NOAA and university researchers have monitored sites inside the Port of Miami since 2018, and reported in Scientific Reports in 2023 that those sites show “periodic extremes in temperature, seawater pH, and salinity, far in excess of what have been measured in most coral reef environments”. Corals grow there anyway.

Which corals is the detail that matters. Diverse coral communities are recorded “growing on artificial substrates at these sites”, and many of the more prevalent species in them “are now conspicuously absent or in low abundance on nearby reefs, owing to their susceptibility and exposure to stony coral tissue loss disease”. Seawalls are holding species the reef has lost.

The authors put the limit on their own finding, and it is worth quoting rather than paraphrasing. “Natural reef frameworks, however, are largely absent at the urban sites and while diverse fish communities are documented, it is unlikely that these communities provide the same goods and services as natural reef habitats.” A tolerant coral on concrete is not a reef.

None of this is a dive site. The work runs on port structures inside a busy commercial channel, which is why the best-known window onto it is a camera. Coral Morphologic, a co-author on the paper, has run the Coral City Camera on a port structure since February 2020 and says it has logged 220 fish species and 27 of Florida’s 48 stony coral species at the one site.

Five Miami watersports businesses sit in a register, and four of them dive

Our own list is short, and its shape says something about the city. The Miami operator list holds 5 businesses, read on 20 September 2026: 4 published by SSI in its register of affiliated training centres and 1 by IKO in its register of affiliated kitesurf schools. Four of the five publish a website there.

The sports do not separate cleanly. Juliet Sailing and Diving is filed under both sailing and diving, which fits a city where the same boat sells both; South Florida Kiteboarding LLC is the sole IKO entry and is the one with no website in its register. SSI additionally rates Ace Diving for freediving, extended range and rebreather programmes, and Underwater Unlimited for freediving. A rating is a listing, not a promise that anything runs this week.

Read the shortness of that list correctly. These are membership registers rather than licences, and a business that never joined SSI or IKO does not appear in either, whatever it teaches. IKO’s own site claims more than 350 affiliated schools against the 291 its feed returns, which is the size of the gap in one register alone. Which registers can be read sets out what each source returns and when it was read.

One practical number is worth carrying regardless of who you book. Divers Alert Network runs an emergency line on +1-919-684-9111, staffed around the clock, and its own guidance is to call 911 or the local equivalent first and to get the injured person to the nearest medical facility, then contact DAN. Hyperbaric treatment is arranged through that route, not looked up in advance. Cover for it is a separate purchase, which is what our dive insurance comparison is for.

Note: Conditions, safety guidance, and visa rules change. Verify current information with official sources (dive operator, coastguard, and the relevant government) before you travel or dive.