Various electromagnetic LWD telemetry systems are disclosed having a wireless repeater positioned on or near the seabed. The wireless repeater receives and demodulates electromagnetic uplink signals and retransmits the uplink signals from the seabed as electromagnetic or acoustic signals. A receiver on the drilling platform or suspended from the water's surface receives the uplink signal and forwards it to a facility for processing and storage. In some embodiments, the wireless repeater takes the form of a sub threaded inline with the drill string with an electromagnetic signal sensor positioned inside the drill string. In other embodiments, the wireless repeater takes the form of a unit that rests on the seabed with electromagnetic signal sensors inserted into the sea bottom.