Often celebrated as a top snorkeling spot and one of the best beginner diving sites in the Florida Keys, Sombrero Reef near Marathon offers a look at how great diving and snorkeling can be. As the largest reef formation in the Middle Keys [1] and a designated Sanctuary Preservation Area (SPA), it holds significant ecological importance.
Marked by the historic Sombrero Key Lighthouse, this site lies approximately four to five nautical miles offshore from Vaca Key and the city of Marathon. For us at Captain Hook’s, it’s one of our longer boat rides when compared to the other sites we visit, but it’s well worth it! Sombrero Reef is definitely one of my favorite spots to see.
This guide aims to provide everything you need to know about Sombrero Reef to have the best time snorkeling and diving.
Why Choose Sombrero Reef? Unique Features & Underwater Appeal
Sombrero Reef’s allure stems from a combination of factors that make it a standout destination in the Middle Keys. Its geological structure, accessibility, marine life potential, and iconic landmark contribute to its enduring popularity.
Spur and Groove Formation
The reef itself showcases a classic “spur-and-groove” formation. This natural architecture consists of coral ridges (spurs) extending up towards the surface, separated by sandy channels (grooves). Some people also call this “finger coral”. This topography creates a diverse underwater landscape with depths varying significantly, ranging from just a few feet near the lighthouse structure to around 30 feet in the deeper channels. Such variation caters well to different preferences and skill levels, allowing snorkelers to explore shallow areas while divers can investigate the deeper grooves and formations. It’s without a doubt one of the best sites we visit thanks to the abundance of fish, the different structure, the varying depths and more.
Plenty to See for Divers and Snorkelers of All Levels
From first-time snorkelers to seasoned divers, the site offers plenty to see for everyone. It’s one of the best locations for handling mixed groups, ensuring that varying abilities, divers and snorkelers can all enjoy the excursion together on the same boat.
While the coral landscape has faced significant challenges in recent years, Sombrero Reef still supports a rich biodiversity. Its status as a Sanctuary Preservation Area (SPA), where fishing and lobstering are strictly prohibited, contributes to healthier and more abundant fish life compared to unprotected areas.
The One and Only Sombrero Key Lighthouse
Dominating the seascape is the unique Sombrero Key Lighthouse. This 142-foot tall, octagonal, cast-iron tower stands on iron pilings driven into the reef. Completed in 1858 under the supervision of George Meade (later famous for the Battle of Gettysburg) [2], it served as a crucial navigational aid until its deactivation in 2015.[1] Exploring right below the lighthouse is tough to do with shallow depths and wave action, but the lighthouse still provides one of the more well known pictures in all of the Keys.
The combination of these elements creates a compelling experience for visitors:
- The varied and accessible underwater terrain
- The abundance of diverse fish sightings fostered by its protected status
- The unique visual appeal of the historic lighthouse
Planning Your Sombrero Reef Excursion: Getting There & Tour Options
It is crucial to understand that Sombrero Reef is not accessible by swimming from land. It is several miles offshore so you’ll need a boat. It’s sometimes confused with Sombrero Beach, a popular spot in Marathon. The beach is entirely separate from the reef.
Option 1: Guided Snorkel/Dive Tours (Most Common & Recommended)
For the vast majority of visitors, particularly first-timers or those without extensive boating experience in the Keys, joining a guided tour is the most practical and often the safest method.
We offer scuba diving and snorkeling trips twice per day. Our tours provide all necessary snorkeling gear (mask, snorkel, fins), safety supervision from experienced captains and mates, and local knowledge to navigate to the best spots within the reef system. For more information about pricing, what to bring, when we depart, etc, visit our snorkeling and dive trip links below:
Option 2: Private Boat / Rental
Visitors with boating experience or those renting a boat can travel to Sombrero Reef on your own. The reef features a system of mooring buoys located on the south side of the lighthouse, designed for vessels to tie off to.
Some important notes:
- Anchoring directly on the reef is strictly prohibited within the Sanctuary Preservation Area to prevent damage to the fragile ecosystem.
- The approximate coordinates for the reef are 24°37′36″N 81°06′39″W.
- A dive flag must be prominently displayed when diving or snorkeling.
- Not adhering to the SPA guidelines can result in costly fines.
What Will You See at Sombrero Reef?
Once at the reef, you’ll finally get to experience the beauty of this reef. The spur-and-groove formations create an awesome environment. Truly one of my favorite places to see!
Snorkelers can glide over the shallower tops of the coral spurs, often just several feet below the surface in some areas. Divers can explore the sandy grooves that can reach depths of 20 to 30 feet. There are plenty of interesting coral formations, like mini-canyons and, historically, large coral structures like the notable elkhorn arch. Again, just be very careful of damaging the reef.
The main draw for many visitors today are the different kinds of fish. Divers and snorkelers can expect to see many of the following:
- Parrotfish: Stoplight, Queen, Rainbow, and Midnight Parrotfish are frequently seen grazing on algae.
- Angelfish: Queen, French, and Gray Angelfish add splashes of color.
- Snapper: Schools of Yellowtail Snapper are everywhere, along with Gray Snapper.
- Surgeonfish: Including the popular Blue Tang (aka Dory)
- Grunts & Chubs: Often seen in large schools.
- Other Reef Fish: Damselfish, wrasse, butterflyfish, sergeant majors, and more.
- Larger Inhabitants: Sightings of Southern Stingrays, Eagle Rays, Nurse Sharks (generally docile bottom-dwellers) and Turtles. Barracuda are also common inhabitants.
While specific sightings are never guaranteed in the wild, the protected nature of Sombrero Reef significantly increases the chances of encountering all sorts of sea life.
The Captain’s Tips for Diving or Snorkeling at Sombrero Reef
Here are some tips from the crew at Captain Hook’s to get the best experience at Sombrero Reef:
- Check the Weather: Wind and wave conditions significantly impact visibility and comfort. Calm days offer the best snorkeling. Check marine forecasts before booking or heading out.
- Wear Reef-Safe Sunscreen: Standard sunscreens contain chemicals harmful to coral. Opt for mineral-based sunscreens (zinc oxide, titanium dioxide) or wear protective clothing like rash guards.
- Do Not Touch or Stand on Coral: Coral is a living animal, extremely fragile, and easily damaged or killed by touch. Maintain buoyancy and keep fins away from the reef structure. Standing on coral is illegal and harmful.
- Never Feed the Fish: Feeding marine life disrupts natural behaviors and can be harmful to their health.
- Use Mooring Buoys, Do Not Anchor: If on a private vessel, always use the provided mooring buoys. Anchoring on coral or seagrass is prohibited and damaging.
- Bring Necessary Gear: we offer quality rental gear, but consider bringing your own well-fitting mask if you have one. A GoPro or underwater camera is popular for capturing memories. Consider Dramamine if prone to seasickness, especially for longer boat rides.
- Stay Hydrated: Bring water, especially on private trips. We provide water and coolers on our boats.
- Listen to Your Captain/Crew: On guided tours, pay attention to your captain and crew. They know how to keep you safe, and they probably have some great tips to see more of what you want.
- Be Aware of Currents: Even on calm days, currents can be present around the reef. It’s easy to get pulled away from the boat. Always be aware of which way the current is pushing you.
Following these guidelines helps protect the reef for future generations and ensures a safer, more enjoyable trip for everyone.
Other Popular Reefs Close to Sombrero Reef
Besides the renowned Sombrero Reef, boaters departing from Marathon can explore several other excellent reef sites nearby:
- Coffins Patch: Located a few miles east of Sombrero Reef, Coffins Patch reef consists of a series of patch reefs rather than a continuous barrier line. Known for often having high concentrations of fish life and generally shallower depths than the outer reef line, Coffins Patch is very popular for snorkeling and offers numerous mooring buoys.
- Delta Shoal: Situated west/southwest of Sombrero Reef, Delta Shoal provides another worthwhile destination. It features some nice coral formations, diverse species of fish, and a good mix of shallow and deep areas.
Common Questions about Sombrero Reef
Can you kayak to Sombrero Reef?
Kayaking to Sombrero Reef is strongly discouraged and generally considered unsafe. The reef sits approximately 7-8 nautical miles offshore from Marathon. This significant distance, combined with exposure to potentially strong currents, unpredictable weather, wind, waves, and boat traffic, makes kayaking extremely hazardous and strenuous, even for very experienced paddlers.
What is the current condition of the coral at Sombrero Reef?
Sombrero Reef’s coral has been impacted by recent environmental stressors. Reports and visitor feedback discuss some coral bleaching and mortality. We constantly working through our Coral Program to help mitigate these effects as much as possible. With that said,Sombrero Reef remains one of the best places to snorkel in Marathon, and all of the Florida Keys.
Why is the coral damaged?
Coral damage occurs due to several factors, including:
- Coral Bleaching: Caused by record-high water temperatures.
- Storm Damage: Lingering effects from events like Hurricane Irma (2017).
- Disease: The ongoing Stony Coral Tissue Loss Disease (SCTLD) pandemic has affected reefs throughout the Keys.
Is Sombrero Reef good for beginner snorkelers or families with children?
Yes, Sombrero Reef is generally good for beginners and families, especially on calm days. It features shallow areas (around 5-15 feet) suitable for snorkeling. However, since it’s an open-ocean reef, always check conditions first; tours are often recommended for novices.
How do I get to Sombrero Reef? Can I swim there from shore?
Sombrero Reef is located approximately 8 nautical miles offshore from Marathon in the Florida Keys. Because of this distance and open water conditions, it is not possible to swim to the reef from shore. Access is exclusively by boat. You can either take your own private vessel or join one of the many licensed snorkeling or diving charter boats operating out of Marathon.
Are You Ready to Visit Sombrero Reef?
Now that you know more about the stunning underwater world waiting at Sombrero Reef, it’s time to plan your adventure! For expertly guided snorkeling tours or diving trips departing directly from Marathon, let Captain Hook’s Marina and Dive Center take you there. We provide everything you need for a safe and memorable excursion to Sombrero Reef and other nearby locations.
Ready to book or want more details? Click here to view all of our available services and book your trip.