I know that there are a couple of questions covering latitude and longitude for water temperature, but overall I'm more interested in the rate of temperature change by depth.
Thought Process: Baseline geothermal gradient is defined as the rate of increasing temperature with respect to increasing depth in the Earth's interior, and approximated at about 25–30 °C/km (72-87 °F/mi) of depth near the surface in most of the world. That's maybe, what, approx. 1°F/75 ft, barring circumstance and variables unknown.
Question: Is there a similar approximate rate by which the temperatures of various depths of water can be estimated, allowing for the same acknowledgement that it's an approximation without context? Or are thermoclines so varied that such an estimated rate cannot be generalized?