South Korea's only land border is with North Korea. The GP was correct that (in this context) for practical purposes South Korea is an "island" because there's

South Korea's only land border is with North Korea. The GP was correct that (in this context) for practical purposes South Korea is an "island" because there's relatively little land travel between North- and South Korea. Map: https://www.google.com/maps/d/viewer?ie=UTF8&hl=en&source=embed&msa=0&ll=35.9302740559874%2C129.32957000000002&spn=4.443673%2C9.831391&mid=1Bu81fI2lSAp-feL9JbPvY6gw3eI&z=7 https://www.google.com/maps/d/viewer?ie=UTF8&hl=en&source=em...