Back in 1996, the North Korean (DPRK) launched the most recent in a series of covert naval submarine missions. However, this one did not go as smoothly as planned.
After running aground and damaging the rudders and propellers, the submarine was captured by the South Korean Navy.
The submarine has been pulled out of the water and is now on display next to a South Korean Destroyer (built by US in 1944) which was decommissioned in 1999.
For ~4000won, you can walk through both of them and even sit and work some of the artillery cannons on the deck of the destroyer.
About 2 minutes drive is the Security Exhibition Hall which has more displays of the history, logistics and memorabilia related to the stand-off war between North and South.
Amazing that while I was in PyongYang (North Korea), the North loved to point out the breaches and infiltration of the Americans in the USS Pueblo, but failed to mention their own transgressions....
Odae-san is Korea's 6th or 7th highest peak and is not that hard of a climb. The scenery rivals the more popular Seorak, but without all of the people. The best time to go is fall when the leaves are all changing color and the cool weather makes for a pleasant day.
The trailhead starts at Sangwonsa (temple). Don't take the bus that stops at Woljeongsa - it's another 8 km to the trailhead from there. I guess you could if you wanted too. I walked the 8km coming back since I missed the bus at Sangwonsa, and it was nice, but I wouldn't recommend it before scaling the mountain.