South Korea and North Korea are divided states and armed-conflict counterparties. Peace building has been pursued since the 1953 Armistice Agreement, but no meaningful results have been achieved. Recently, tensions have risen in the transboundary maritime areas around the NLL, the provisional maritime delimitation line between the two Koreas. Two Koreas' unique circumstances require case studies between divided and/or armed-conflict States focusing on maritime areas. From the first case of maritime delimitation under the peace treaty between Israel and Jordan to the divided States and/or the armed-conflict States case, i.e. the East and West Germany case, the Cyprus case, the Northern Ireland case, the Israel-Jordan case), this paper aims to extract legal implications and lessons for the peaceful management of transboundary maritime areas and waters surrounding the NLL. Till now two Koreas have only agreed on transboundary maritime management with the issue-specific approach. For the future, in addition to the achievement of the issue-specific approach to the transboundary maritime management, it needs to consider the integrated maritime management, such as the MSP.