Sargassum in Belize: Is It Really That Bad?

Over the past several years, there has been a lot of reporting about Sargassum in Belize and how this floating seaweed can have negative effects on the experience of tourists who visit Belize.

In this article, we take a look at several aspects of Sargassum in Belize:

• What is Sargassum and where does it come from?
• When is the Sargassum season in Belize?
• Which parts of Belize are affected by Sargassum?
• What are the negative effects of Sargassum in Belize?
• Is the Sargassum problem getting worse in Belize?
• What is being done to mitigate the problems associated with Sargassum in Belize?

What is Sargassum?

According to NOAA, Sargassum is a genus of large brown seaweed (a type of algae) that floats in island-like masses and never attaches to the seafloor.

If you look closely at Sargassum while it is still floating in the water, you will see that it is a collection of branches with leafy structures attached to them, along with round, berry-like structures that make up the plant. These berries are actually are actually gas-filled structures, which are mostly filled with oxygen. These gas-filled berries add buoyancy to the plant structure and allow it to float on the surface.

Sargassum tends to form large clumps in the sea, and when these clumps collect in larger quantities, they can become huge rafts of floating seaweed that can stretch for miles across the sea.

While we will read about some of the negative effects that Sargassum can have on tourism when it hits land, Sargassum also has positive effects on sea life, as it forms a floating habitat that provides food, refuge, and breeding grounds for an array of animals such as fishes, sea turtles, marine birds, crabs, shrimp, and others.

Sargassum also serves as a primary nursery area for a variety of commercially important fishes such as mahi mahi, jacks, and amberjacks.

Where does Sargassum come from?

Until about 2011, Sargassum was found only in the the Sargasso Sea, which is a vast patch of ocean named for the genus of free-floating seaweed called Sargassum. The Sargasso Sea is unusual in that it is the only sea without land borders. It is located entirely within the Atlantic Ocean and defined only by ocean currents.

The US National Ocean Service describes how the Sargasso Sea got its name:

The Sargasso Sea is a vast patch of ocean named for a genus of free-floating seaweed called Sargassum. While there are many different types of algae found floating in the ocean all around world, the Sargasso Sea is unique in that it harbors species of sargassum that are ‘holopelagic’ — this means that the algae not only freely floats around the ocean, but it reproduces vegetatively on the high seas. Other seaweeds reproduce and begin life on the floor of the ocean.

NOAA National Ocean Service

Historically, the majority of Sargassum was located in the Sargasso Sea in the western North Atlantic. However, in 2011, the geographic range of Sargassum expanded.

A newly established population of the floating seaweed, driven by shifting wind patterns, is now thriving in the open ocean. This region is called the “Great Atlantic Sargassum Belt.” Massive amounts of Sargassum from this area are transported west into the Caribbean Sea, the Gulf of Mexico, and tropical South Atlantic via ocean currents.

When the Great Atlantic Sargassum Belt first formed and Sargassum seaweed started to make landfall in Belize, as well as in other areas of the Caribbean, the Sargassum season began in the spring and ran through the summer, roughly from April until August. However, over time, Sargassum has been appearing earlier in some years and staying around later.

During my time living in San Pedro, it felt as if the Sargassum season didn’t really end until we had the first large storm of the latter part of the Hurricane/Rainy Season for the year.

Sargassum in Belize: Which parts of the country are affected?

Obviously, as Sargassum is a type of seaweed which floats along the surface of the Caribbean Sea, the coastal areas are the areas which suffer the negative impacts from Sargassum in Belize.

While much of the land mass of Belize is not coastal, and there are no real direct impacts from Sargassum in Belize away from the coast, many of the most important tourist destinations, including the islands of Ambergris Caye and Caye Caulker, as well as coastal destinations such as Hopkins and the Placencia peninsula, do have east-facing shorelines, which are the primary areas that are negatively impacted by large quantities of Sargassum when it comes ashore.

Some water front areas in the country, such as the western sides of the cayes, including the popular Secret Beach area of Ambergris Caye, are not affected by Sargassum. Also, Corozal, in northern Belize, is not really affected either, as the Corozal shoreline sits on a bay rather than the open Caribbean Sea.

When I was operating my rental units in San Pedro, I often told perspective guests that I did not view San Pedro, or Belize in general, as a ‘beach destination,’ rather, I saw it more as a snorkeling, diving, sailing, sport fishing, adventure destination. With the world’s second largest barrier reef around a quarter mile offshore, there is simply not enough wave action to produce the wide, silky, sandy beaches that one might find in more traditional beach locations.

Also, there is a lot of sea grass between the reef and the shoreline, so in many areas, swimming from shore is not a great experience. In my view, even some of the best beach areas in Belize are not what one might think of when imaging a beach vacation. I always wanted to make sure that my guests, most of whom came for 30-90 days, had realistic expectations, so I would explain the beach situation to my guests.

However, while Belize might not be a traditional beach destination, there is still a large concentration of resort properties and other rentals right on the Caribbean Sea front, so when the eastern facing shores are inundated with Sargassum, there are some really negative effects for the tourism industry.

What are the negative effects of Sargassum in Belize?

As we’ve noted above, when Sargassum is floating on the open sea, it provides an important habitat for different species of sea life. However, once large mats of Sargassum begin to wash up on the beaches, there are a number of negative impacts.

One of the primary negative effects that is produced by Sargassum when significant quantities land on shore is the very unpleasant odor which is emitted when the algae begins to decompose once it is on the beach.

Not only is the odor of the decaying Sargassum unpleasant, most people describe it as smelling like rotten eggs, but exposure can also be harmful to humans. NOAA notes that “Sargassum decomposing on the beach produces hydrogen sulfide, a gas that smells like rotten eggs, which can cause respiratory irritation.”

NOAA also describes some of the other potential negative affects of Sargassum in Belize, or anywhere else in the Caribbean where it comes ashore in massive quantities:

Massive amounts of Sargassum can form brown tides nearshore, smothering fauna and flora — including coral reefs. Sargassum mats may also clog water intake pipes used in critical infrastructure (for example, in desalination plants that produce drinking water). Sargassum also contains high levels of arsenic and other heavy metals, organic contaminants, and marine debris.

NOAA: National Ocean Service

When a location, San Pedro, for example, has a massive influx of Sargassum, the two primary negative effects which one notices are the strong, sulfuric odor and the large amount of decaying seaweed lying on the shoreline. It is not much fun trying to go for a swim when the first ten-fifteen feet of water from the shoreline is piled with decaying, off-gassing algae.

While living in San Pedro, I had a friend who had been living on the island for some thirty years. She had a beautiful home, built on a very large lot right on the sea front. Between her home and the beach area, she had a large tropical garden; thus, her house sat 30-40 yards back from the beach area.

She had a nice deck on the second floor of her home, and this was also where most of her living area was located. With her windows open, she always had a wonderful sea breeze, and the deck was a fantastic place to sit, sip your favorite beverage and gaze out over the reef.

However, after the Sargassum began to come ashore in large quantities every year, she had to close her windows and stay inside for months at a time, as she was quite sensitive to the hydrogen sulfide which was released by the Sargassum as it decayed. The smell and the irritants contained in the gas made her quite physically ill. I spoke to a number of people who were likewise affected by the irritants released by the Sargassum.

I also recall that shortly after Belize’s largest hotel, Alaia, had opened in San Pedro, I saw an army of guys working with pitchforks and rakes trying to remove the Sargassum from the beach in front of the property every day. These guys were working more than 10 hours a day, removing thousands of pounds of seaweed from the beach every day, yet at the end of the day, there was still a mountain of Sargassum on the beach.

The Alaia had placed some huge boulders in the water to create three, pretty little artificial coves in front of the property, hoping to create a safe, pleasant place for guests to swim; however, with the first inundation of Sargassum, they discovered that they had created three large traps into which the Sargassum could flow and then get trapped.

Naturally, there is a north to south current flow on the east side of Ambergris Caye, but any assistance the property might have had from the current pushing some of the Sargassum further south was prohibited by the artificial coves built by the hotel developer. Eventually, Alaia had to disassemble their pretty artificial coves.

Sargassum in Belize: Is the problem getting worse?

The Alaia was not the only party struggling to fight the Sargassum as the inundations got worse over the years. With most of the island’s tourism-related restaurants and bars located along the shore, the San Pedro Town Council, along with the local businesses, hired crews to go out and manually remove Sargassum from the beach areas in the town core every day.

Teams of guys with wheel barrows, rakes, and pitchforks were dispatched daily to remove Sargassum and despite long hours, and valiant efforts, it often appeared to be a never-ending task, with little progress to show for all of the work. Also, manually removing the Sargassum also led to some beach areas losing a lot sand in the process.

While there have been some improvements and changes to the removal methods over the past several years, you can still see crews from the Town Council out raking Sargassum on a regular basis.

With a population of only around 420,000 Belize, of course, has limited resources which it can throw at the Sargassum problem, but the tourism sector in our much larger neighbor to the north, Mexico, has also faced significant challenges dealing with Sargassum removal on the beaches of the Mexican Riviera.

Mexico’s beaches, unlike most of the other countries in the region, stayed open during much of the Covid lockdown, but around this time, there was also a massive growth in the Great Atlantic Sargassum Belt, and the beaches of Cancun and Playa del Carmen were inundated to such an extent that the Mexican government enlisted the services of the Mexican military, particularly the Navy, to assist with Sargassum removal, and despite these enormous efforts, they still struggled to keep up with the influx.

Countries around the Caribbean have been looking to new technologies and methodologies to fight Sargassum, and some private businesses in Belize have brought in some mechanized beach rakes and other devices, but recently, the government of Belize has also looked to technology to assist in protecting the countries primary tourism market.

As we’ll see in the section below, Belize has recently acquired a few new tools in this battle against Sargassum, and while this is commendable, I still don’t think that there will be an end to manually removing Sargassum from the beaches in Belize anytime soon.

What is being done to mitigate the problems associated with Sargassum in Belize?

According to the San Pedro Sun, on Friday, April 11th 2025, the Belize government announced “a collaborative effort between the Hol Chan Marine Reserve, the Ministry of Blue Economy and Marine Conservation, and the Belize Social Security Board to address the environmental challenges of Sargassum influxes on Ambergris Caye.”

These three agencies collaborated to mitigate the effects of Sargassum in Belize, and specifically on Ambergris Caye by purchasing two state-of-the-art modified vessels, which act as harvesters designed to collect and remove Sargassum efficiently before it reaches the shore.

The acquisition of the two Sargassum harvesters was part of a plan put in place by the Hol Chan Marine Reserve, which also includes the building of several Sargassum barriers.

At the ceremony to dedicate the two new Sargassum harvesters, Jerome Palma, acting Chief Executive Officer of the Belize Social Security Board, shared that the Social Security Board decided to invest funds into the project as a means to protect a vital part of the Belize economy, the tourism activities in the primary tourism market in the country.

At the dedication ceremony for the Sargassum harvesters, Andre Perez, Minister of Blue Economy and Marine Conservation for the national government, reported that it took about a year and a half of planning to get the harvesters in place, and the initial cost of the project was two million Belize dollars.

The San Pedro Sun also reported:

Community members expressed optimism about the project’s potential to alleviate the Sargassum problem, which has previously overwhelmed local cleanup efforts. The harvesters are expected to complement ongoing manual removal initiatives, providing a more sustainable and scalable solution. Officials also emphasized plans for continuous monitoring and adaptive management to ensure the project’s long-term success.

San Pedro Sun

Of course, only time will tell if these new boats will provide substantial assistance to the public and private sector on Ambergris Caye with keeping the beaches free of decomposing Sargassum, and thus mitigate the negative effects of these huge mats of floating seaweed.

Hopefully, Belize is moving in the right direction with a program to assist with the Sargassum problem, however, we must be realistic, as there are much larger countries, with larger tourism markets, fighting the same battles, and they are still finding it to be quite challenging.

Final thoughts on Sargassum in Belize: Is it Really That Bad?

Before moving to Corozal on the Belize mainland, I lived in San Pedro town where I owned a building with several rental units. I always warned my guests about the possibility of a Sargassum influx during the season, and I honestly told them that some tourists were really put off when their stay coincided with a bad invasion of the sea weed.

However, I also told my guests, that even with Sargassum along the sea front, I still went walking/running every day for several miles along the beach areas and sea walls in town, and only on a few occasions, did it really bother me. Of course, I didn’t enjoy my morning exercise as much when there was a lot of Sargassum around, but I did not let it keep me from doing my daily activities.

I may have felt differently if my property were sea front, along an area which accumulated lots of rotting, smelly Sargassum, and I understand why some folks would at times choose not to dine at beach front restaurants, but I found it to be a personal inconvenience rather than something that greatly impacted my daily life.

I was also fortunate enough to own a little boat while living in San Pedro, and it was fairly easy to get out on the water and away from the smelly Sargassum, or to cruise around to a sand bar on the west side of the island where there was no rotting seaweed.

While I applaud the local and national governmental organizations for working together to acquire the new harvesters, I also hope that they will take a lesson from some of the other cases in which new, more modern, equipment was purchased or received from a donor to help alleviate a problem, but the needed training for operations and maintenance of the equipment was neglected.

Here, I am thinking about new trash compacting trucks, which were acquired via a donation from Taiwan or Japan, or perhaps the building of new solid waste disposal stations transfer stations, which were built on the Belize mainland in cooperation with international donors, but still sit unused, years after their construction.

Finally, if you are considering a move to Belize, you might want to check out our book: Belize FAQs: A detailed guide for those interested in moving to Belize. In the book, there are more than 150 pages of Belize FAQs at your fingertips. And Belize FAQs is available in both paperback and Kindle formats.