Two eminent lawyers, Saul and Daniel Hofileña, father and son, authored an elucidating monograph,” Turmoil at the South China Sea” which to me is a veritable dictionary of basic yet misapplied terms. Let us review a few:
Archipelago. A group of islands inter-connected by waters and other natural features, so closely interrelated that such islands, waters and other features form an intrinsic geographical, economic and political entity, which historically have been regarded as such. Lifted from the United Nations Convention of the Law of the Sea (UNCLOS), but redacted by me.
Archipelagic sea lanes. Maritime channels established by an archipelagic State for the continuous and expeditious passage of foreign ships and aircraft through and/or over its archipelagic waters.
Baseline. A low-water line marked along the coast as shown in large-scale charts and officially recognized by a coastal and/or archipelagic State. This is called “normal baseline” the first method; the second method establishes a “ straight baseline” by drawing straight lines from selected points along a country’s shoreline. However, the “straight baseline” must not depart to any appreciable extent from the general direction of the coast. In accordance with the UNCLOS, both baselines may join the outermost points of the outermost islands and/or drying reefs, provided that the main islands are included within the baselines. The Philippines follows the archipelagic baseline method established by Article 47 of the UNCLOS.
Contiguous zone. This is an area adjoining or bordering the territorial sea of a State which should not go beyond 24 nautical miles from the baseline that determines the breadth of the State’s territorial sea. The UNCLOS grants the coastal and/or archipelagic State the right to enforce its laws within said zone whenever customs, fiscal, immigration and sanitary laws are violated.
Continental shelf. In the case of coastal States, the UNCLOS defines this as the sea bed and subsoil of the submarine areas that extend beyond the territorial sea and the natural prolongation of the State’s land territory up to the outer edge of the continental margin, or to a distance of 200 nautical miles measured from the baseline.
Exclusive Economic Zone (EEZ). This shall not extend beyond 200 nautical miles from the State’s baselines. A coastal State has the sovereign right to explore, exploit, conserve and manage all kinds of natural resources, living or nonliving, in its EEZ. It can also make artificial islands and structures and conduct marine scientific research. However, Article 87 of the UNCLOS grants other States freedom of navigation, overflight, the laying of submarine cables, pipelines and other internationally lawful uses of the sea compatible with the Convention.
High Seas. What is not included in any EEZ, territorial sea, internal and/or archipelagic waters is called the High Seas. These are waters beyond the purview of any one State. All are accorded the right to navigate, fly over, lay cables and pipelines, construct artificial installations allowed by International Law, fish, conduct scientific research without impeding other States from doing the same. The High Seas is reserved for peaceful purposes only, so no State may exert sovereign rights over any part of it.
Island. We learned this in Grade 4, but legally speaking, it is a naturally- formed area of land surrounded by water and which is above water even at hide tide. For example, Spratly Island ( Lagos), the Spratly Islands Group (Kalayaan) and Thitu Island, (Pag-asa) A low-tide elevation is not an island because it disappears during high tide
Reef. A chain of rocks, corals or a sand ridge, near or at the surface of the water, for example, Mischief and Subi Reefs which we refer to as Panganiban and Zamora, respectively.
Rocks. Geological features that cannot sustain human habitation nor have an economic life of their own when located in a body of water are mere rocks. These are natural substances composed of different materials fused together into solid lumps. (Article 121  UNCLOS)
Shoal. Scarborough Shoal (Bajo de Masinloc or Panatag), Second Thomas Shoal (Ayungin) are sandbanks or sandbars that make the waters around them look invitingly shallow.
Territorial sea. That belt of water immediately surrounding a country’s land mass is called the territorial sea. In the case of archipelagos, this includes the archipelagic waters in between the islands. According to the UNCLOS, the territorial sea should not exceed 12 nautical miles from the established baselines.
The Area. Mysterious as it sounds, this is nothing more than the deep seabed and subsoil beyond all EEZs, maritime zones, continental shelves, territorial seas and the national jurisdiction of any State. According to Article 137 of the UNCLOS, no State, no natural person nor corporation can appropriate any portion of The Area because the resources found there belong to mankind.
These are but a few terms, go get the book for the definitions of 9-dash line, Arbitral Tribunal, artisanal fishing and how our national boundaries meandered since the 1898 Treaty of Paris.