Separate lines: Challenges and opportunities of differentiated seabed and water column boundaries
The significant extension of claims to national jurisdiction offshore in recent decades has led to a proliferation in overlapping maritime claims and the resulting need for the delimitation of maritime boundaries between coastal States. Prior to 1982, maritime delimitation beyond territorial sea limits predominantly concerned the delimitation of the continental shelf. With the introduction of the EEZ concept, States have been faced with the need to delimit both the continental shelf and the overlying water column, including in some instances the need to delimit the water column above their already delimited continental shelf. While there has been a clear trend towards coincident maritime boundaries to delimit both the seabed and water column, this has not always been the case. This chapter traces the development of the continental shelf and EEZ regimes and their relationship. Evolving approaches towards maritime delimitation are then outlined. Examples of State practice where separate delimitation lines have been defined are highlighted as are key challenges and opportunities related to such practice. The potential for further differentiated seabed and water column boundaries as well as other analogous practice to emerge in the future is then explored and concluding thoughts offered.