Question of conservation of energy in this thought experiment

Hi,

I have a somewhat silly question about something I cannot figure out properly.

I have a cylinder with a piston inside. The cylinder is sealed and filled with air. The piston is free to move back and forth inside the cylinder, but are also sealed so no air can escape no matter how much the piston compress the air inside the cylinder.

If this system is submerged into a fluid, water for example, the water pressure will push the piston further into the cylinder so the air inside becomes compressed according to the water column above.

When I pull the system up to the water surface, the air inside the piston finally expands to initial volume.

So to the question:
If the piston is a magnet, and the cylinder is a coil, and I repeat the experiment, the moving magnet piston will generate an electric current through the coil if the coil is shorted or loaded.

We all know that energy is allways conserved, so:
What difference in work, and how would it "feel like", to put the system in and out of the water if the coil is:
1. Not loaded
2. Loaded

Br.

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