At some coasts, water temperatures are lowered by upwellings that carry deep, cold water up to the surface.

Upwellings occur when strong offshore winds blow out towards sea. As the surface water is pushed away from shore, cold water from the deep travels up to take its place. In addition to lowering temperatures, upwellings also increase both visibility and the nutrient content of the surface waters. This makes for excellent diving when upwellings are present.