The little red light is hooked up between the neutral and the ground wire, and as the other posts indicate, it means somewhere in the shore power system the neutral and load wires have been switched. Stick your mutimeter (carefully) in the marina socket--Assuming you are using 110V, if you measure 110V between the neutral and the ground, talk to them about their wiring.
On a 15 amp North American circuit, the neutral is the wider blade and the ground is the round plug.
On a 30 amp circuit, the ground is the blade with the extra bend. Looking at the socket, if the ground is at 6 o'clock, the neutral should be at 10 and the load should be at 2.