Upwelling
The major upwellings in the ocean are associated with the divergence of currents that bring deeper, colder, nutrient rich waters to the surface. There are at least five types of upwelling: coastal upwelling, large-scale wind-driven upwelling in the ocean interior, upwelling associated with eddies, topographically-associated upwelling, and broad-diffusive upwelling in the ocean interior.
Thimble jellyfish
Larvae of the thimble jellyfish are the most common cause of seabather's eruption in the Caribbean and the Gulf of Mexico. This is an itchy rash of small red papules that develops in the areas that were covered by the bather's swimwear or hair. The condition does not occur immediately, but after the bather has showered or the skin has dried, killing the jellyfish larvae which react by discharging their stinging cells. In Florida, most cases occur between March and August. A similar condition occurs on the east coast of North America after exposure to the larvae of the sea anemone "Edwardsiella lineata".