Thermal differences in the sea and their effect on diving
How temperature gradients in water layers affect diving and marine creatures.
Water is not one temperature from the surface to the bottom. Thermal differences affect diving and the environment together.
The thermocline
The thermocline is the boundary between a warm water layer above and a colder layer below. You feel it as a sudden change in temperature during descent.
Effect on visibility
At the thermocline the dividing boundary looks like rippled glass or a hazy layer. Visibility is sometimes noticeably affected.
Effect on buoyancy
Density changes with the thermocline, which means lead settings that work well above the thermocline may not work with the same efficiency below it.
Effect of the thermocline on marine life
Many fish concentrate at the thermocline because plankton accumulates at this boundary. The diver who knows the thermocline knows where life is.
Knowing the sea layer by layer gives you a deeper understanding of what you see and where you find it on every dive.