St. Maarten Sargassum Watch
An honest daily read on where the seaweed is — and, more often, where it isn't. Satellite-tracked each day and checked by our team on the ground.
Clear across the island.
Satellite imagery over the past 7 days shows little floating sargassum in the Atlantic waters off the east coast, and little floating sargassum off the western Caribbean shore. The west- and south-facing (leeward) beaches are your best bet for clear water; the exposed east coast typically sees the most.
Beach conditions are set automatically each day from NOAA CoastWatch / USF AFAI (7-day) satellite data, and refined by our team on the ground.
- Clear — Little to no sargassum reported in the last 24 hours. Comfortable to swim.
- Moderate — Noticeable seaweed along the shoreline. Still swimmable, but patchy.
- Heavy — Thick sargassum on the sand and in the shallows. Expect an odour on warm days.
Beach-by-beach conditions
Select any beach on the map, or in the list below, to see today's report. Colours are set from the daily satellite reading for each coast and refined by our team.
Official sources, updated daily
Our report is a local, on-the-ground read. For the basin-wide satellite picture and multi-day outlook, these are the authorities we watch too.
Météo-France — Sargassum forecast, Northern Islands
The official French forecast for St. Martin / St. Barths, updated regularly through the season.
NOAA CoastWatch — Daily Sargassum Inundation Risk
A daily satellite-derived risk map for the whole Caribbean basin, from the U.S. NOAA laboratory.
University of South Florida — Sargassum Watch System
Daily satellite imagery and monthly outlook bulletins from the lab that pioneered basin-wide tracking.
The log
-
Clear
Caribbean coast clean and swimmable. East-facing Dawn Beach and Guana Bay carrying heavy sargassum; Orient Bay and Oyster Pond moderate. Light east-southeast winds.
-
Clear
Similar picture — leeward beaches clear, windward east coast moderate to heavy. Great Bay raked and tidy by early morning.
-
Moderate
A brief southeast wind shift pushed light sargassum onto Simpson Bay's eastern end overnight; cleared by afternoon. East coast heavy.
-
Clear
Excellent conditions island-wide on the Caribbean side. Only the Atlantic-facing beaches affected, as usual.
What sargassum actually is
Sargassum is a free-floating brown seaweed that drifts across the Atlantic on wind and current. Out at sea it is a thriving habitat for turtles, fish and crabs. It only becomes a nuisance when large mats wash ashore and begin to decompose, which is when the familiar sulphur odour appears.
Since 2011 the Caribbean has seen larger seasonal influxes from what scientists call the Great Atlantic Sargassum Belt. Volumes vary enormously from one year — and one week — to the next, which is exactly why a live, local read is more useful than any single forecast.
When is sargassum season in St. Maarten?
The influx typically runs from around April through August or September, with the heaviest arrivals usually between May and August. The winter and early-spring months — roughly December to March — are generally the clearest.
None of this is fixed. A calm week in peak season can leave every beach pristine, and a stray wind shift in an otherwise quiet month can bring a patch ashore overnight. Treat the calendar as a tendency, not a promise.
Which beaches are affected — and which stay clear
The single most useful thing to understand is that sargassum is driven onto windward, Atlantic-facing shores. On St. Maarten that means the east coast — Dawn Beach, Guana Bay, Oyster Pond, and the French Atlantic beaches like Orient Bay and Le Galion — sees the most.
The Caribbean-facing, leeward beaches on the west and south are largely sheltered and are clear far more often than not. Maho, Mullet Bay, Cupecoy, Simpson Bay, Great Bay, Little Bay, Long Bay and Baie Rouge rarely see significant sargassum. If a clean beach day matters to you, that is where to look first — and the map above is colour-coded so you can see it at a glance.
How we help our guests stay ahead of it
Most of the SeaLaVie SXM collection sits on the calm, Caribbean side of the island — Simpson Bay, Cupecoy and the western neighbourhoods — so the great majority of our guests are simply unaffected. When conditions do shift, our team knows within hours and will happily point you to the clearest water that day, or rearrange a beach plan around it.
If a stretch of protected coastline and dependable swimming matters to your trip, tell us — we will match you with a property positioned for it.
Sargassum questions, answered
When is sargassum season in St. Maarten?
The seaweed influx generally runs from April through August or September, with the heaviest arrivals usually between May and August. December through March is typically the clearest window. Volumes vary year to year, so a live report is the most reliable guide.
Which St. Maarten beaches have the least sargassum?
The Caribbean-facing, leeward beaches on the west and south of the island are clear most often — Maho, Mullet Bay, Cupecoy, Simpson Bay, Great Bay, Little Bay, Long Bay (Baie Longue) and Baie Rouge. The Atlantic-facing east coast, such as Dawn Beach and Guana Bay, sees the most.
Is it safe to swim when there is sargassum?
Small amounts of floating sargassum are harmless. Large decomposing mats are best avoided — they can be unpleasant to wade through and release a sulphur odour on warm days. On heavy days, simply choose a leeward beach instead.
Will sargassum affect my SeaLaVie SXM stay?
Most likely not. The majority of our properties are on the sheltered Caribbean side of the island, which is clear far more often than not. If conditions change during your stay, our team will point you to the clearest beaches that day.
Want a stay on the calm, clear side of the island?
Most of our collection sits on the sheltered Caribbean coast — the beaches that stay clear most of the year. Tell us what you're after and we'll match you with the right home.