The hydrosphere that surrounds the hard rocks, have been adventurer's paradise since aeons. But the water mass that surrounds about 3/4th of the globe and which has been labeled as the 'heritage of humanity' has been a serious bone of contention both for the contemporary civilization as also for the future generation.
Immediately beyond the shore line follows the continental shelf. Formed of continental rock mass, at times the continental shelf extend up to 700 nautical miles as in Alaska, Siberia, Grand Bank areas off North America and Dogger's Bank near Europe. Simultaneously near many countries like Peru coast the shelf extends only for a few kilometers. The continental shelf is followed by the Continental Slope, after which the continental rise and deep ocean floor follows. These areas are known together as the Continental Margin These seemingly innocuous geological details would loose their meaning if the resource importance and simultaneous political bickering for these maritime frontiers are not elaborated. It also needs to be explained as to who really owns these areas and if there is a contest for the ownership, what are the remedial measures.
Analysis of the resource importances of these areas is important before the geo-strategic contest for the same is elaborated. The continental margin may have about 40% of all known oil and natural gas reserves. Mind you, most of these areas are not explored as the present technology is not sufficient for deep-sea mining. The second important resource being fishing, the ocean nearly supplies about 13% of world's animal protein consumption. Also the ocean beds are known to keep almost inexhaustible amount of poly-metallic nodules. These nodules contain within them large amount of scarce metals (on the land) in them like the manganese, cobalt and nickel and harvesting them from seas would eventually be much cheaper then mining them on land.
The ocean is also known to be a great source of energy. The present technology is not known to make profitable leeway into geo-thermal and tidal energy but the future has great potentialities for them.
Given these tremendous potentialities, especially with respect to increasing shortage of food, oil and minerals, it is but obvious that major powers of the world would not only clamor for an everlasting control on the marine resources. Increasingly more and more countries are also claiming territorial and economic jurisdiction off their shores. The United Nation Laws Of Sea contends that the territorial jurisdiction of any country (with a sea boundary) extends up to 14 nautical miles. Thereafter 200 nautical miles beyond the territorial seas is known as Exclusive Economic Zone. The High Seas (area beyond the 320 kms or 214 nautical miles) has been assigned to be the 'Heritage of Mankind'. Such delineation, however, has created more problems than solving them. If such a jurisdiction is allowed uncontested, the major naval powers would face a great threat in transit through straits. For example, if Spain is given a territorial jurisdiction off its southern coast, it can literally control the passage of every ship in the Mediterranean Sea. Under the principle of innocent passage, the merchant ships can be allowed to pass over the territorial waters, but nuclear submarine and aircraft carriers can hardly fit in to that category. Also the same definition if left uncontested can give unparalleled influence to Iran in Persian Gulf. There is also contention on the definition of the territorial waters on other count. Some countries, notably the United States, want the definition of the territorial water to extend up to the continental shelf (as they have wider shelf on the east coast which are also the high fishing zone).
There are disputes in other regions of the world. The most notable among them are the Kurile Islands (between Russia and China), Spratly Island (6 countries in South China Sea region are contestants most important being China) and Sir Creek (between India and Pakistan) among several others.
Beyond the disputes the resource potential of the oceans are more than realized. At least 8 Governments are known to actively pursue the research and mining in ocean floor. The most notable among them are U.S, Canada, Russia, France, Germany and Japan.
Though the raging debates would continue till eternity as to who actually controls the Oceans or the land submerged beneath it, but if the High Seas are really the 'Heritage Of Mankind', some ways must be sought to bring equitable distribution of wealth that gets generated from it. That wealth should also not ignore the landlocked countries like Nepal, Bhutan, Afghanistan or Burkina Faso. Some international agency must be created which mines the mineral resources from the sea-bed and distributes the profit equitably. But going by the past record of all major powers that ideological upfront seems too utopian and probably too unrealistic.