Just to put this in a thermodynamic perspective:

Due to the Law of Entropy, any heat removed from one part of a system must be added in a greater quantity to another part of the system. Therefore, to remove heat from the oceans would mean transfering heat to the air plus the heat output of the work done to transfer the heat, which would in turn warm the oceans more than doing nothing.

The only solution to the heating of oceans is to create, globally, the inverse effect of the greenhouse effect, cooling the atmosphere enough to lower sea temperatures. A giant volcanic eruption is one potential way of doing this...but it isn't exactly something that we, as humans, can cause easily. This would cause a cooling of the Earth's atmosphere by changing an external effect on the system: the effects of the sun. Thus it is not bound by localized thermodynamical properties mentioned in the first scenario.