On a skinny wooden post in bold red writing a sign warns "Swimming Area Closed."
"It almost looks like it's supposed to be there," one beachgoer said.
"It makes me very nervous," said another.
But when the sun is shining and the water is warm, it seems some people (and definitely some dogs) just can't resist diving in.
"This is the closest place for him to swim and for him to run around," Lisa Scholder said of her dog.
Scholder is what you'd call a regular at Picnic Island Beach. Health advisory or not, she goes approximately 3 to 4 times a week.
"I don't swim a lot, but I mean I'll wade in a little bit with my dog," said Scholder.
This week, the Hillsborough County Health Department identified both Picnic Island Beach and Davis Island Beach as having high levels of enterococci bacteria. The presence of that usually indicates fecal pollution, which may come from storm water runoff, pets or human sewage.
Signs warning people not to swim are posted near both of the beaches, but yet you can still find people going in every day.
So how dangerous is it really?
"The real risk is that you could get sick and become fairly ill from this bacteria," said Steve Huard, the Hillsborough County Health Department spokesman.
According to the Health Department, bacteria-infected water can cause gastrointestinal issues, infections, rashes, and can even be life threatening for those with compromised immune systems.
"It makes good sense to avoid the water when we post an advisory," said Huard. "Why take the risk?"
Animals are also not immune to the bacteria. Experts advise pet-owners wash them immediately if they go swimming in the water when bacteria levels are elevated.
To read the latest beach testing results go to http://www.hillscountyhealth.org/absolutenm/templates/?a=102 .