Here is how it will work. Anchor a large tunnel to the sea floor like a buoy but in several locations around the tunnel to hold it fast to the sea bed.
Position it to where one open end opposes the current at depth where the cool water is and the other open end at the surface faces away from the current. What happens is a difference in pressure is created at both ends and when a pressure difference is created flow occurs. That is the beauty of Bernoulli's principle. Cool water is bought up from below thus mixing with the warm water at the surface. The tunnel is neutrally buoyant with the top end just under the surface. Remember it can only work where there is a current. No current, no difference in pressure. Also, enough electricity can be generated for millions of people in Florida.