Florida residents and vacationers, especially those on the west coast between the Tampa Bay and Charlotte Harbor estuaries, often find themselves beset by the unpleasantries of red tide, a phenomenon that is neither red, nor a tide. Red tide is a euphemism for a harmful algae bloom (HAB) of which there are many different kinds worldwide. Florida red tides are generally associated with a bloom of the toxic dinoflagellate, Karenia brevis. K. brevis is known to produce toxins, which kill finfish, taint shellfish to the point of being hazardous for human consumption, cause respiratory distress in marine mammals and humans and make shore conditions repulsive to tourism and dining. Like K. brevis, other HAB species worldwide have similar deleterious effects, some much worse, and the ocean circulation lessons learned from K. brevis are, at least in a general sense, applicable elsewhere.