A tour in one of the world's most heavily-fortified borders

GANGHWA ISLAND, South Korea — Along the demilitarized zone (DMZ) between the two Koreas lies this island, where the tension between the militaries of the two countries silently simmers.

- By JOSEPH PEDRAJAS

The connecting waters of Yesong and Han Rivers is the only thing that borders this island from North Korea. This makes it one of South Korea's closest frontiers to its neighboring communist state, just 1.8 kilometers away.

But it also feels one the farthest, as one local who also works as a docent put it. It's because the silent tension at the border is always at risk of escalating into conflict.

On this island there are military observation posts. Day and night, they watch every move of their North Korean counterparts across the other side, and vice versa.