Islamorada Snorkeling| Top Spots to Explore

Islamorada snorkeling is incredibly popular among those vacationing in this part of the US, and in fact snorkel trips in Islamorada, FL offer some of the finest reefs to be found anywhere in the Florida Keys.

Although Key West and Key Largo snorkeling tours may be better known, some of the best snorkeling tours in the Keys actually involve taking trips to the Islamorada snorkeling sites featured in this guide.

In addition to Big Pine and Marathon Key snorkeling – also in the Middle Keys – several reefs located close to the six islands of the Islamorada area provide some of the best snorkeling available in the entire US. 

Cheeca Rocks, Donut Hole, Hens and Chickens  and Alligator Reef snorkeling actually provide visitors with some of the best snorkeling in Islamorada – and they’re all covered in this article. 

You’ll have to take a boat trip out to these reefs, but that’s not at all difficult with so many to choose from. There are plenty of group snorkeling tours in Islamorada, FL, or you can charter a boat privately. 

Read on to find out which of the various snorkeling tours available in Islamorada might be right for you – as well as why it’s wise to visit these fascinating examples of underwater life while you still can. 

This guide also includes an Islamorada snorkeling map. You can see the map immediately below this introduction to snorkeling in Islamorada, FL, before we move on to covering each site in more depth. 

In this post:


Islamorada Best Snorkeling Spots Map


Alligator Reef

Alligator Reef Lighthouse
Photo Credit Happiness is Traveling

Marking one of the most popular Islamorada snorkeling spots, Alligator Reef lighthouse is a landmark located just north of the reef itself. The lighthouse is just a few nautical miles from Indian Key, an offshore island close to Upper and Lower Matecumbe Keys.

Though Alligator Reef has suffered some damage in recent times, the chance of seeing the lighthouse helps to make Islamorada snorkeling at Alligator Reef worthwhile. It’s not only the lighthouse itself that is a draw, either: there is plenty of underwater life that can be observed in the stretch of sea around the structure. 

There are two main causes of damage to the reefs of the Islamorada area. One is Hurricane Irma, after which Alligator Reef, among others, suffered storm damage. The second cause is Stony Coral Tissue Loss Disease.

This condition has adversely affected many of the reefs off the Florida Keys, including major sites such as Dry Tortugas National Park and Alligator Reef. Conservation efforts are therefore underway to address this, and this involves transplanting coral from unaffected sites such as Cheeca Rocks to encourage new growth. 

Given the name, you may also expect an Alligator Reef Islamorada snorkeling trip to be fraught with danger. This is not the case, however. Despite the moniker, there are no alligators to be found there. 

The name in fact comes from USS Alligator, one of the many shipwrecks whose remnants can be found beneath the sea. This vessel ran aground on the reef in 1822 when it was only two years old, during a mission to rescue ships that had been seized by the pirates that frequented the waters of the Caribbean. 

Islamorada Snorkeling
Eel at Alligator Reef

Although the crew did their utmost to save it, USS Alligator was eventually given up, and it was set on fire to blow it up after all salvageable assets had been removed. This was to prevent pirates from getting their hands on the booty. For this reason, only small charred fragments were left behind.

In times past the key danger was indeed posed by the reef itself. It was previously the site of many a shipwreck, before the lighthouse station opened in 1873. The skeletal tower is 41 meters tall and has been automated since the early 1960s.

A great white shark was spotted in the waters here in April 2016, however. It was spied from the HappyCat, a vessel belonging to the Robbie’s Islamorada snorkeling company that was docked on Lower Matecumbe Key. This was an incredibly rare occurrence, and not at all typical of Islamorada snorkeling tours.

Alligator Reef can only be reached by boat. Taking a group or private charter is thus the best way to see the reef, and these can be booked locally via companies such as Robbie’s snorkeling in Islamorada. 

It’s an ideal spot for snorkelers and scuba divers, not least because visibility tends to be very good. The Sanctuary Preservation Area here is clearly marked by buoys and covers around two square miles.  

The reef offers some of the best snorkeling in Islamorada, and during your visit you may see the likes of nurse sharks, grey snapper, barracuda, sting rays, parrotfish, sea turtles, spiny lobsters and of course an abundance of coral. You may also be lucky enough to spot a school of dolphins from the boat as you travel out to sea.

Hens and Chickens

The Hens and Chickens Sanctuary Preservation Area (SPA) is located southwest of Plantation Key, within the Florida Keys National Marine Sanctuary. It is a shallow patch reef offering some of the finest snorkeling near Islamorada.

This reef at the center of Hawk Channel was so named due to the shape of the coral reef, which looks like lots of baby chicks clustered around a larger adult hen when viewed from above, in the air. This is no doubt why many refer to it as ‘Hens and Chicks’ instead. 

The depth varies between about 10 and 20 feet, and it’s a great site for both snorkelers and divers to explore. At the site you can see waving purple sea fans as well as mounds of star, Christmas tree and brain coral. Some of these reach up to around 15 feet, which makes them an impressive sight that scuba divers can swim around. 

For beginners, this is one of the best snorkel trips in Islamorada to take. Even for children, it can be a good introduction to the underwater world as the depth is relatively shallow. Colored tropical fish such as angelfish and blue tang should keep them interested too. Larger schools of fish are often seen, as well as white sponges and reef crabs. 

Although the waters are relatively shallow, this is one of the top places to snorkel in Islamorada as the marine environment is both colorful and unique. For this reason many Islamorada snorkeling charters will include this spot on their itinerary.

As with Cheeca Rocks, Hens and Chickens is not too far from the shore. You’ll still need to travel to the site by boat, but it involves a shorter trip than traveling to the outer edge of the reef.

Trips typically run daily during good weather and you may spend around half a day visiting Hens and Chickens as well as other sites such as Alligator Reef, Davis Reef, Rocky Top and Morada. 

Like Alligator Reef, Hens and Chickens has a landmark to mark the spot. In this case it’s the tower formerly used as the Hen and Chickens Shoal Light, which was active during some of the 20th century.

Hens and Chickens reef has also been affected by Stony Coral Tissue Loss Disease, though considerable efforts are being made to limit the spread of this damaging condition affecting many Florida reefs. 

Cheeca Rocks

Cheeca Rocks reef

Cheeca Rocks is a remarkable site, due to the fact that the coral here has somehow managed to survive the outbreaks of Stony Coral Tissue Loss Disease that are severely damaging much of the other coral in the area.

Studies are being carried out to try to determine why this might be. Samples are also being removed for transplantation at other sites like Alligator Reef, with the hope that this will result in new coral growth – and ideally, resistance to this damaging condition.

There are other factors at play too. In late 2020, the University of Maryland Center for Environmental Science and the National Oceanic and Atmospheric Agency (NOAA) joined forces to assess various US reefs, and identified the acidification of the ocean, global warming, overfishing and coral disease as major ongoing threats. Notably, climate change was named by NOAA as the main cause of reef deterioration.

Coral reef in Cheeca Rocks
Tagged coral in Cheeca rocks

With these combined threats, Cheeca Rocks provides visitors with the unique opportunity of seeing a relatively unaffected coral reef. Many who plan to do some snorkeling in Islamorada, Florida Keys therefore don’t want to miss this one off their itinerary.

Size wise, Cheeca Rocks is one of the smallest Sanctuary Preservation Areas, occupying only about 0.05 of a square nautical mile. This reef can be found around a mile south east of Upper Matecumbe Key, and like Hens and Chickens it’s a shallow reef.

As well as being the site of intense scientific study, Cheeca Rocks does permit anchoring, as long as mooring buoys are used to avoid damaging the delicate coral formations. Plenty of brain, star, fire and soft corals can be seen at Cheeca Rocks, as well as other sea life.

The patch reef is just a short boat trip away, and is a popular stop on many Islamorada snorkeling trips. At times the water can be greener in colour than that found further out to sea, as there is more algae present.

Coral in Cheeca Rocks

This translates into a food source for the ocean creatures that frequent Cheeca Rocks, which helps to attract many species of fish, green eels, parrotfish, blue tang and angelfish. You may also see West Indian Sea Egg urchins, Queen conch and sea turtles.

Other intriguing sea life forms often witnessed at Cheeca Rocks may include sea rods, plumes and fans as well as Branching Vase Sponges. The site is sometimes referred to as Cheeca Gardens, due to the colorful and almost floral appearance of much of the reef.

Like Hens and Chickens, Cheeca Rocks is one of the premier family spots for snorkeling near Islamorada, FL. The shallow patch reef is good for beginners, and it’s about the closest you’ll get to Islamorada snorkeling from the shore.  

Donut Hole

When approaching Donut Hole by boat it’s easy to see the reason for its name, as the reef is ring shaped. Many people who make the trip are rewarded with sightings of sea turtles, as well as plenty of colourful fish – both individually and in schools.

Donut Hole forms part of French Reef. This is one of the top spots for snorkeling from Key Largo or Islamorada, and is also pretty good for rookies. 

The site has various underwater caves to explore, as well as rocky ledges, and these provide a home for a range of sea life forms. Being deeper than other nearby places, the French Reef area is also popular with divers.

In addition to the Donut Hole, divers and snorkelers visit French Reef to see caverns like the Sand and Hard Bottom caves, Hourglass cave and Christmas Tree cave. The latter is a big cavern that divers can swim through, and is named for the Christmas Tree Worms inhabiting the area. 

With a depth of around 25 to 30 feet, Donut Hole and other parts of French Reef are good for experienced snorkelers as well as open water divers. There are some breathtaking coral formations at the site, and snorkelers can also see these as they rise up to about 15 feet from the sea bed. 

This triangular reef is around six nautical miles from Key Largo, and is worth visiting due to its ledges, arches and caves in addition to the underwater life and of course the donut hole itself. The rocky formations tend to be named for their shapes – Hourglass cave being a typical example. Christmas Tree Cave, meanwhile, is so known because of the big star-shaped, conical coral mound jutting out from it. 

A profusion of sponges can be seen at the Donut Hole, so it’s worth venturing a little further out to sea – as well as a little deeper – if you want to witness some slightly more unusual underwater sights.


As you can see, snorkeling in Islamorada, FL is a popular activity – and very deservedly so. The best snorkeling in Islamorada, FL beats much of that found elsewhere in the Keys, as well as in the rest of Florida.

From sea sponges at the Donut Hole to unspoiled Cheeca Rocks, easy Hens and Chickens and the impressive reefs around Alligator Reef Lighthouse, there’s a whole new underwater world waiting for you when you go snorkeling in Islamorada.

 Looking for more Florida Keys information to plan your trip? Check out all of our Florida Keys Guides HERE.

About the author
Kristin Young