Red Tides
Red tides are generally caused by the invasion of red and brown algae that is poisonous to the fish in certain areas and toxic to humans. If you can see a fluorescent orange glow under the water, a good rule of thumb is to avoid swimming in that location, no matter how enticing it looks. A good rule of thumb is if there are dead fish in a place, you really shouldn’t swim in the water that the fish died in.