How can I get GPS maps for South Korea?

Episode 1132 (1:59:23)

Mike from Bath, Maine
Garmin Nuvi 55

Mike is going to South Korea and needs to download maps to use. Leo says that using a smartphone may be the best option. If he buys a separate GPS, he can order maps and install them via USB. Mike says that Korean GPS are terrible. has maps for South Korea that works with Garmin GPS.