The ICOW Maritime Claims Data Set

The maritime claims data set follows the general guidelines on the ICOW home page.

A maritime claim is defined as explicit contention between two or more nation-states over the use of a specific maritime zone. Official government representatives (i.e., individuals who are authorized to make or state foreign policy positions for their governments) must make explicit statements contesting the usage of that maritime zone, typically for matters like fishing or navigation.

Please note that the ICOW Project and its directors do not take or endorse official positions on any maritime claims. Our goal is to identify cases where nation-states have disagreed over specific issues in the modern era, as well as measuring what made those issues valuable to them and studying how they chose to manage or settle those issues. Inclusion/exclusion of specific cases, and coding of details related to those cases, follows strict guidelines presented in the project's codebooks (which are available below).

Measuring Claim Salience

The salience of maritime claims is measured by a 0-12 index, which includes up to six points each for the claim's challenger and target states (one point each for six indicators of salience). For more details see the Hensel, Mitchell, Sowers, and Thyne JCR article listed below in the data set references section of this page.

Project Participants

Current Status

We have released data on maritime claims, claim salience, claim militarization, and peaceful settlement attempts for the Western Hemisphere and Europe for the years 1900-2001. Work is underway for the rest of the world, with the Middle East nearly complete and work on both Asia/Oceania and Africa making slower progress; data for these additional regions will be released as soon as possible.

RegionStatusNumber of Claims
(and Dyadic Claims)
Western Hemisphere Data collection completed (1900-2001) 45 distinct maritime zones
(68 dyadic claims/2374 dyad-years)
Europe Data collection completed (1900-2001) 42 distinct maritime zones
(75 dyadic claims/854 dyad-years)
Africa Research currently underway  
Middle East Research currently underway  
Asia and Oceania Research currently underway  

Beginning in 2019, we have started publishing quarterly reviews of events occurring in any of the four current ICOW issue types -- territorial, river, maritime, or identity claims -- during three-month periods. These reviews describe such events as the beginning of new claims, the occurrence of military or other provocations related to the issue, and attempts to manage or settle the issues peacefully. Besides posting each quarterly review at the above link, we also offer a DuckDuckGo custom search that allows users to search for reviews that contain such terms as names of territories, countries, or leaders. (For now, this is limited to ICOW's quarterly reviews of news over territorial, river, maritime, or identity claims, covering events since the beginning of 2019. In the future, we plan to expand this search to include access to summary web pages for each of the more than 1200 claims identified by the ICOW project, which will be created as part of the next external grant that the ICOW project receives.)

Descriptive Details

Version 1.1 of the ICOW Maritime Claims data set includes claims over a total of 87 distinct maritime zones. Some of these areas are claimed by multiple claimants at various points in time or are settled temporarily only to see renewed claims later (perhaps related to expanded claims to offshore maritime zones), so these claims include 143 dyadic claims that together cover 3228 dyad-years. These claims have been managed through 95 militarized interstate disputes and 496 peaceful settlement attempts (including bilateral negotiations, non-binding third party activities like mediation or good offices, and binding third party activities like arbitration and adjudication).

Data Set References

The first published article to use the ICOW Maritime Claims data set was Hensel, Mitchell, Sowers, and Thyne's 2008 JCR article:

The first paper to focus specifically on maritime claims is:

Download the Codebooks and Data

All ICOW data sets may be downloaded freely, but we request several professional courtesies from users:

Coding Manuals

The following links provide access to the coding manuals and other useful information:


The maritime claims data set is included in the main ICOW data download, along with the territorial claims and maritime claims data sets:

Please note that this, like all ICOW data sets, uses the list of country codes in the COW interstate system. Please see that list for help in identifying which countries were involved in the events included in this data set, or for any questions about when each country was considered a sovereign, recognized state.

Contact Information

The ICOW Maritime Claims data set is collected and maintained by Sara McLaughlin Mitchell at the University of North Texas. Please contact her with any questions about the data set:
Last updated: 21 November 2019
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