Sargassum at Cannon Beach (John Pennekamp): today's conditions
First bulletin for this beach lands with tomorrow morning’s update.
Cannon Beach is a small swimming beach inside John Pennekamp Coral Reef State Park, on the ocean side of Key Largo in the Upper Keys. It faces east onto the Atlantic, and the water stays shallow well past the sand.
This page tracks sargassum at Cannon Beach day by day: what is showing along the waterline, a 0 to 5 rating to place the day, and the FanGass map putting the beach alongside other Keys locations. The update lands each morning, before you commit to the drive down the Overseas Highway.
Cannon Beach (John Pennekamp) on the sargassum map
What to know about this beach
The park sits on the ocean side of Key Largo, yet this is not a typical exposed shoreline. The reef tract a few miles offshore absorbs much of the swell before it reaches land, so water arrives at the beach with little force. Sargassum that clears the reef drifts into the cove rather than being thrown onto it.
That has a practical consequence: what comes in leaves slowly. With almost no wave energy at the shore, a mat pushed in by an easterly or southeast breeze can sit along the sand for several days, where an open coast would have broken it up and moved it along. The small size of the swimming area works the same way, since a modest amount of weed covers a noticeable share of it.
Frequently asked questions
Why does sargassum reach Cannon Beach if a reef protects it?
The reef flattens swell but does not stop floating weed. Rafts ride the surface, drift over it on an easterly breeze and settle in the cove, where there is little wave energy to carry them back out.
How do I check the beach before entering the park?
FanGass posts a 0 to 5 rating and the observed condition for Cannon Beach every morning. Looking before you pay the park entrance tells you whether snorkeling gear is worth unpacking today.
Does sargassum affect snorkeling here?
A thick band along the waterline clouds the shallows and makes entry awkward from the sand. On low-rating days the shallow snorkel spot a short swim offshore, with its old cannons, is easy to reach.
Is there another beach inside the same park?
The park has a second beach, Far Beach, plus other water access points. Exposure is broadly similar, so use the map to compare Cannon Beach with other Key Largo spots before deciding where to spend the day.