Many are aware of the recent eruption of the Kilauea Volcano on the island of Hawai’i. The lava flows this eruption has produced have entered the ocean at several locations, expanding the island’s shoreline and even creating a small new island offshore. As an individual who has spent many a working hour assessing how shorelines (or normal baselines, as they are referred to under the Law of the Sea) will impact territorial sovereignty and boundaries with neighboring countries, I thought it would be an interesting exercise to assess how this latest eruption could affect the sovereign limits of Hawaii and the United States.

The island of Hawaii, showing locations of the volcano summit and Active Fissure 8, the origin of recent lava flows.

To begin this exercise, I pulled an island polygon for Hawai’i from an early June edition of OpenStreetMap — prior to the eruption. I then pulled the same feature from the latest OpenStreetMap. It speaks volumes to the power of OpenStreetMap and dedication of its contributors that the lava flow areas and expanded shoreline have been added and updated since the eruption in early July.

Active lava flows and ocean entry, showing area of expanded shoreline since the eruption.

An area measurement of the land added since the eruption yields about three sq. km. (shown in dark red on the map above). To assess the impact of the expanded shoreline on the 12 nautical mile territorial sea, I ran two simple “envelope of arcs” calculations in CARIS software (their Limits and Boundaries module). For one calculation I used a pre-eruption normal baseline, and for the other a post-eruption normal baseline. With each calculation, I was able to identify the contributing base points along the normal baseline as well as construction lines emanating from each to create the 12 nautical mile territorial sea limit.

Calculation of 12 nautical mile territorial seas showing contributing base points along the new and older shoreline, construction lines, and the territorial sea limit.

In this real-world example, the expanded shoreline of the island adds about nine square kilometers to the territorial sea area of the island of Hawai’i.

So does this mean there is a direct correlation between newly formed land and area added to a country’s sovereign space? Not really. In the case illustrated above, the expanded shoreline has been built out seaward enough on a slightly convex coast that it adds new contributing base points to the 12 nautical mile territorial sea. However, if the lava were entering the ocean in an area of coastal concavity, bay, or inlet, we might see several square kilometers of new land that does nothing to change the outer limit of the territorial sea.

Diagram illustrating lava filling in a coastal concavity, versus lava expanding on an area of coastal convexity. The latter might contribute to an expanded territorial sea.

Of course, this new “land” created by the eruption is quite fragile and susceptible to collapse and rapid breakdown, so just as quickly as we’ve added 9 square kilometers to the United States’ sovereignty, it could get washed away.

The island formed by lava flow in last month’s eruption. Photo @ USGS

Map data @ OpenStreetMap

What’s the deal with these new maritime boundaries from old, never fully defined or bilaterally agreed upon land boundaries? I’ve recently come across three of these scenarios, all, strangely enough, with former or current Dutch possessions.

In 2007, Guyana, a former British colony, had its maritime boundary with Suriname, a former colony of the Netherlands, awarded by the Permanent Court of Arbitration. In reading through court proceedings, their lack of an established land boundary felt like the elephant in the room. Much of their land border follows the western (Guyanese shoreline) bank of the Courantyne River, but at various points in history, the United Kingdom and later independent Guyana claimed the thalweg of the river rather than its shore. Today, it seems like the western bank is de facto accepted as the international boundary between them, though there is a large territorial dispute in the south over the New River Triangle. Despite the ill-defined land boundary, the Court was able to comfortably begin their maritime boundary on the low tide coast, and the maritime space between them is now well-defined and undisputed.

The map shows the 2007 maritime boundary extending from the de facto and disputed land boundary.

Saint Martin and Sint Maarten, which share an island in the Caribbean Sea, are both still connected to their colonial powers, France and the Netherlands, respectively. Sovereignty on the island was initially split in 1648, and not much additional definition to the land boundary seems to have been applied since. The eastern land boundary terminus (LBT) is in dispute as sovereignty over Oyster Pond is in question. And yet, in 2016, France and the Netherlands agreed to a maritime boundary dividing their Caribbean possessions. The eastern section of the maritime boundary begins at a point defined in WGS-84 on the coast, giving us a little more information about what must be the location of their land boundary. The western section, however, begins off the coast of Oyster Pond, allowing both countries space between their disputed land boundary and now established maritime boundary. This Agreement was ratified in 2017.

The map shows the undelimited land boundary and the 2017 established maritime border.

France also signed a boundary agreement with Suriname in 2017, marking the second current or former Dutch possession to have one of its maritime boundaries recently delimited. In this Agreement, they established a closing line across the mouth of the Maroni River where it empties into the Atlantic Ocean and began their maritime boundary from this point. Meanwhile, it is completely unclear as to the location of their land boundary in the Maroni River. France and the Netherlands made several draft attempts at formalizing the land boundary between their colonial possessions in South America, but due to a variety of reasons, including the disputes over the Maroni River and the source of the Kutari River and World War II, none of the agreements were ever signed.

The map shows the de facto and disputed land boundary along with the 2017 unratified maritime boundary.

There are a variety of factors which may contribute to the establishment of a maritime boundary beginning from a de facto or disputed land boundary. A primary motivation may be economic. There are an abundance of resources to exploit in the ocean—oil, natural gas, fish—all of which are more easily and efficiently obtained when the maritime boundary is well-defined.

Another factor may be a difference in perceived stakes/value. Territory on land is tangible: that tree over there, it’s definitely on the French side of Saint Martin. Maritime space, on the other hand, is vast and difficult to define. The average individual can only interact with maritime boundaries on maps and in media coverage. It is therefore easier for the public to allow for compromises to be made to delimit boundaries at sea than those on the ground.

In addition to the above reasons, land boundaries have centuries of baggage that go along with them. All of those agreements, drafts, meetings, and attempts at defining the boundary through here or there add up. Families for centuries may have thought they belonged to one country, but when a boundary is formally defined, end up in another. This causes all kinds of social issues. There aren’t people living in newly defined maritime space. Occasionally, historic fishing rights are impacted, but these are often addressed in negotiations or adjudication.

Or perhaps these successful maritime negotiations were the result of being a former or current colony of the Netherlands in the western hemisphere.

Ever since Nicaragua brought a case against Colombia to the International Court of Justice (ICJ) in 2016, entitled: “Question of the Delimitation of the Continental Shelf between Nicaragua and Colombia beyond 200 M from the Nicaragua Coast,” the Court has been faced with the question of whether or not there is a hierarchy to continental shelf claims. In other words, would a coastal State’s 200 nautical mile (M) exclusive economic zone (EEZ) entitlement to the continental shelf and superjacent waters under Part V of UNCLOS prevail over an opposing coastal State’s claim to an extended continental shelf under Part VI? The former being based on a legal entitlement of all coastal States and the latter based on a geomorphologic claim by a coastal State that its shelf satisfies the stipulations set out in Part VI of UNCLOS beyond 200 M, which must be subsequently reviewed and approved by the Commission on the Limits of the Continental Shelf (CLCS).

In its 2012 Judgment on the maritime boundary between these two States, the ICJ loosely defined the 200 M seaward limit of Nicaragua’s EEZ entitlement as the “approximate eastern limit of the relevant area,” but stated that Nicaragua had “not established that it has a continental margin that extends far enough to overlap with Colombia’s 200-nautical-mile entitlement to the continental shelf, measured from Colombia’s mainland coast. . . .” This new case is Nicaragua’s attempt to recast its scientific findings in hopes of convincing the Court that it has an entitlement to the continental shelf beyond 200 M from its baselines.

Map from 2012 ICJ Judgment Colombia v. Nicaragua

Assuming for a moment that Nicaragua’s claim to an extended continental shelf in the western Caribbean Sea were to be upheld, and if this area were found to overlap Colombia’s 200 M EEZ entitlement, the question then remains as to whether or not this overlapping area of continental shelf entitlements (seabed and subsoil only) would require delimitation. Or, on the other hand, whether Colombia’s 200 M entitlements would automatically prevail due to the legal nature of the EEZ entitlement.

State practice seems to favor the position that extended continental shelf claims are reserved for areas of seabed that fall beyond 200 M from any coastal State’s baselines. In the general vicinity of the western Caribbean Sea, Mexico, Cuba, and the United States have all made extended continental shelf claims in the Gulf of Mexico. However, those claims have all been limited to the areas known as the “Eastern Gap” and the “Western Gap.” None of the extended continental shelf claims have ventured into the 200 M EEZ of neighboring States.

Map from The Heritage Foundation

In the North Atlantic, the enclaved French islands of St. Pierre and Miquelon illustrate very clearly this respect of the 200 M EEZ entitlement. In its consideration of an extended continental shelf claim for these dependent islands, France has recognized that the extended continental shelf in the area south of St. Pierre and Miquelon’s maritime corridor starts beyond Canada’s 200 M EEZ entitlement limit. Their hopes of acquiring a portion of this potentially oil-rich outer continental shelf area would have them making a discontinuous “leap frog” claim over Canada’s 200 M EEZ entitlement, and thus landing in the outer continental shelf beyond any Canadian legal entitlement.

Map from st-pierre-et-miquelon.org

It is important to note that the ICJ’s ruling in this case will only impact sovereign rights to the seabed and subsoil, since Nicaragua would have no EEZ entitlement beyond 200 M from its baselines. Therefore, the more seaward location of the San Andres archipelago, which the Court has already ruled are part of Colombia’s sovereign territory, would give Colombia the sovereign rights to the resources found in the shelf’s superjacent waters regardless of which State might be granted the sovereign rights to the continental shelf below.

On March 6, 2018, Australia and Timor-Leste signed a treaty establishing a maritime boundary in the Timor Sea. The oil-rich maritime area in question had been a source of conflict leading up to Timor-Leste’s independence in 2002, with tensions between this tiny country and its larger neighbor to the south only growing worse since. In negotiations, Australia sought a boundary along its continental shelf, while Timor-Leste aimed for a median line dividing the maritime space between the two. In 2016, Timor-Leste filed a “notice instituting conciliation” with the Permanent Court of Arbitration (PCA), which has since facilitated negotiations between the two nations to resolve the dispute. It is of note that this was the first ever PCA conciliation to be initiated under the UN Convention on the Law of the Sea, and it has successfully led to a bilateral maritime agreement.

The new continental shelf boundary is made up of 13 points (TA-1 through TA-13), all of which are connected by geodesic lines, and the exclusive economic zone boundary is defined by five of these (TA-5 through TA-10), with the eastern half of the EEZ boundary following the principle of equidistance. On both sides, the continental shelf boundary abuts existing “zones of shared sovereignty” in place between Australia and Indonesia. Within these areas, Australia maintains rights to the seabed and Indonesia to the EEZ/water column. This arrangement between Australia and Indonesia stems from 1972 and 1997 agreements, from which the newly established Australia-Timor-Leste boundary has gleaned several of its turning points.

Map depicting the new Australia-Timor-Leste boundary, as well as zones of shared sovereignty between Australia and Indonesia. Dashed blue lines are strict equidistance lines.

Due to the existence of shared sovereignty zones and the history of delimitations between Australia and Indonesia in the Timor Sea, an interesting term is found in Article 2 of the treaty: It defines several of the continental shelf boundary segments as “Provisional.” The treaty elaborates on this in Article 3, essentially making accommodations for a future delimitation between Timor-Leste and Indonesia by allowing the “Provisional” segments defined in Article 2 to be adjusted under certain conditions.

A major aspect of the treaty involves existing oil fields and the dividing of oil revenue. The path of the maritime boundary leaves Timor-Leste with sovereignty over several oil fields previously shared with Australia in the now-defunct Joint Petroleum Development Area (defined in 2002 by the Timor Sea Treaty). A “Special Regime Area” is now defined surrounding the Greater Sunrise Fields, and the treaty includes language to split revenue from these fields depending on where oil is piped and processed, however always in favor of Timor-Leste.

Map depicting the Greater Sunrise Fields and the delimited Special Regime Area. Source: Annex C, Treaty between Australia and the Democratic Republic of Timor-Leste Establishing their Maritime Boundaries in the Timor Sea.

The establishment of a maritime border and signing of a treaty is seen as a great win for stability in this region, and especially for the country of Timor-Leste, which has come away with solidified sovereignty over known oil reserves — a potentially major stimulus to a long-struggling economy. However, the treaty also raises some questions; How will boundary negotiations go between Indonesia and Timor-Leste? And, based on the outcome of the Australia – Timor-Leste treaty, will Indonesia attempt to renegotiate its maritime boundaries with Australia?

A full version of the treaty can be accessed here.

The International Court of Justice (ICJ) delivered a Judgment on 2 February 2018 that resolved the land and maritime disputes between Costa Rica and Nicaragua. The Court delimited the maritime boundary, reaffirmed Costa Rican sovereignty over Isla Portillos, and ordered the Nicaraguan government to remove a military camp located in the wetland of Isla Portillos.

This is not the first time that arbitration has occurred to resolve disputes between the two countries. Their boundary was arbitrated by the United States during the 19^th century, and in 2010, Costa Rica initiated proceedings against Nicaragua at the ICJ following the establishment of a Nicaraguan military camp in Isla Portillos. The Court ruled in 2015 that the presence of the camp violated Costa Rican sovereignty.

Nicaragua withdrew its troops from Isla Portillos in accordance with the 2015 Judgment but constructed a new camp within the area in the following months. Costa Rica filed new proceedings in January 2017 and argued that the Court had already ruled that Costa Rica held sovereignty over the area.

In 2014, Costa Rica initiated a case against Nicaragua concerning the maritime boundary following unsuccessful bilateral talks and the Nicaraguan allocation of disputed maritime space to several oil companies. The Court decided to join the proceedings of the Isla Portillos and maritime disputes, which led to this Judgment.

The Isla Portillos dispute stems from conflicting interpretations of a 19^th century border treaty and arbitration. The features described in the treaty have disappeared due to coastal recession, which prompted the Court to redefine the boundary in the absence of these historic features. They ultimately allocated Isla Portillos to Costa Rica and Harbor Head Lagoon to Nicaragua.

Map depicting the boundary along Isla Portillos. Source: ICJ Judgment.

The Court delimited a single boundary along the territorial sea, exclusive economic zone (EEZ), and continental shelf using the principle of equidistance.

For the Caribbean maritime boundary, strict equidistance was modified by the Court to give the Corn Islands (Nicaragua) half-effect. The Court also addressed several other issues concerning this boundary, including a frequently changing coastline and the overlapping entitlements of third States.

The Caribbean maritime boundary delimited by the Court. Source: ICJ Judgment.

Erosion along the mouth of the San Juan River frequently alters the shape of the Caribbean coastline. Taking this into account, the Court established a fluid starting point of the maritime boundary that lies wherever the mouth of the San Juan River is currently located, and a fixed point two nautical miles out to sea.

This approach is similar to the Court’s treatment of other cases involving volatile coastlines. In Honduras v. Nicaragua, the Court established the starting-point of the maritime boundary at a distance of three nautical miles seaward from the mouth of the Coco River due to the instability of the coastline in that area.

The Court treaded cautiously regarding overlapping entitlements of third States in the Caribbean. Colombia and Panama have both delimited boundaries in the relevant maritime area in this case. The Judgment emphasizes that the establishment of the maritime boundary is without prejudice to any overlapping claims or entitlements of third States, as the maritime space of third States cannot be identified in the proceedings of the case.

The Judgment’s effect on third States remains to be seen, however it will likely have significant impact on future maritime boundary negotiations in the Caribbean, especially if Colombia and Panama stake additional claims in the area.

The Pacific maritime boundary is more straightforward than that of the Caribbean. Half-effect was given to the Santa Elena Peninsula (Costa Rica) to obtain a more equitable division of the relevant maritime space.

Map of the Pacific maritime boundary. Source: ICJ Judgment.

Both States have hailed the proceedings as a victory in government press releases. The Judgment will likely have a significant effect on Costa Rican–Nicaraguan relations and maritime boundary negotiations in the Caribbean Sea involving other States.

The full text of the Judgment can be accessed here.