We conducted an undersea magnetic induction (MI) communication experiment in the South China Sea to demonstrate the feasibility of a rotating permanent magnet transmitter. The rotating permanent magnet transmitter is placed on the floating platform for generating the inductive magnetic field, and a ferrite-rod coil with the glue-filled waterproof seal is hung in the seawater as a receiving antenna. This data is a received magnetic signal at a depth of 30 m in seawater.