The topic of the present post, maritime borders in Ancient Greece, was inspired by N. Papazarkadas’ comments on my previous post.
Most of Attica’s borders, as well as those of many other Greek poleis, were delimited by the sea. What does this mean, concretely? Did the coasts mark the borders, or were the borders offshore? To put it more simply: were there territorial waters in Ancient Greece?
The formula κατὰ γῆν καὶ κατὰ θάλατταν, found in some Eretrian proxeny decrees, and offering protection to the city’s benefactors “on land and sea,”  would seem to argue for the existence of territorial waters. However, it is likely that protection, in this case, was not granted beyond the harbor, as specified in the fifth-century BC asylia agreement between Oiantheia and Khaleion in Lokris . I tend to believe that only harbours and internal bays were viewed as an extension of the chora.
Nowadays, the territorial waters of a country extend 12 nautical miles from the coast, although this distance is contested. Whether such a distinction between the open sea and coastal waters existed in Antiquity is moot . Judging from the scant evidence on this issue, I would argue that no such distinction existed.
If maritime borders existed, we should be able to find traces of them in the epigraphic record. A Cretan inscription reports a border quarrel between the cities of Lato and Olous about claiming possession of a wreck stranded on a desert island between them . This case shows that an islet located between two cities could be the source of a border conflict, even if, in this case, the object of the quarrel was not about the island itself, but about the possession of the freight. Nevertheless, this suggests that the maritime extension of a city’s influence could be contested and challenged in some very concrete cases.
This episode led me to reexamine the legal status of the rocky islands of Petaliai, in the southern Euboean gulf, between Attica and Euboea. Were they considered to be Athenian, Eretrian, or even Styrian before 400 BC? An Archaic inscription suggests that Eretria’s maritime influence (control?) extended as far as the Petaliai Islands in the 6th century BC . The meaning of “influence” is elusive, but in any case it seems that the Eretrians viewed the Petaliai as a limit in the Archaic period. H. Van Wees believes the islands mark the limit beyond which sailing a military ship required a wage to be paid to its sailors . Regardless of the true meaning of the text, I don’t think that the waters delimited in the inscription can be considered the “territorial waters” of Eretria. Instead, the rocky islets delimit an area in which internal administrative and financial rules were enforced by the Eretrians. These delimitations do not have an international character and are not recognized by the neighboring states. Thus, the scope of these maritime delimitations would be similar to the ones found in the Thasian Law for wine trade, banning Thasian ships to import foreign wine within the area delimited between Athos and Pacheia (IG XII Suppl. 347). Maritime delimitations did exist, but they were not markers of absolute sovereignty (like the land borders) and concerned instead the financial policy of a polis .
The epigraphic record yields more cases of disputes about fishing. Was fishing limited by territorial delimitations? Where there fishing rights in the Greek World, comparable to the pasture rights found in the inscriptions? Was an Athenian fisherman allowed to fish near the Euboean shore? We do not know any regulations or restrictions on coastal fishing or even medium to long-distance fishing. The freedom of (pacific) navigation seemed to rule. According to Plato, “the fisherman shall be allowed to hunt in all waters except harbors and sacred rivers and pools and lakes” (Laws, VII, 824 b). In the Roman period the sea was res communis and the fish were res nullius . This was probably the case in the Greek World too, although J. Dumont holds an opposite view. According to him, legal texts related to fishing allow to position “horoi on a fluctuating water chora” . But the examples he cites – for instance the agreement between Troezen and Arsinoe, recently re-edited by fellow C. Carusi – do not concern maritime delimitations but instead fishing installations built on the shore.
Greek cities could generate revenues from the sea by exploiting tuna fisheries or by taxing the sale of fish in the marketplace, but it seems they did not own the exclusive right to “own” the sea as an extension of their territory, nor to establish maritime boundaries, which were, from a political and legal point of view, comparable to their land borders and recognized as such.
 See for example D. Knoepfler, “Décrets de proxénie et de citoyenneté,” Eretria XI (2001) Lausanne, Payot, no.5, l. 16 ; no VI, l. 20 and his remarks p. 49. The expression appears in various Athenian decrees, se for example the treaty of alliance between Athens and the Boiotians (A. G. Woodhead, Inscriptions. The Decrees. «The Athenian Agora», 16  Princeton, no. 34).
 H. van Effenterre – F. Ruzé, Nomima. Recueil d’inscriptions politiques et juridiques de l’archaïsme grec I (1994) Collection de l’Ecole française de Rome, Rome, no. 53 l. 4.
 See G. Purpura, “‘Liberum Mare’, Acque territoriali e riserve di pesca nel mondo antico, in J. Napoli (ed), Ressources et activités maritimes des peuples de l’Antiquité, Actes du colloque international de Boulogne-sur-Mer 12, 13 et 14, Mai 2005, Cahiers du littoral 2, no. 6 (2008) 533-554. I am grateful to C. Carusi for this information.
 H. Van Effenterre, “Querelles crétoises,” REA 44 (1942), pp. 38–40. See also A. Chaniotis, Die Verträge zwischen kretischen Städten in der hellenistischen Zeit (1996) Stuttgart, Steiner, 327-328.
 IG, no. XII, 9 1273-4. See D. Knoepfler, “Une cité au cœur du monde méditerranéen antique. Erétrie et son territoire, histoire et institutions,” Cours et travaux du Collège de France, Résumés 2007-2008, Annuaire 108e année, 604 ; van Effenterre – F. Ruzé, op. cit., no. 91.
 H. Van Wees, “Those Who Sail Are to Receive a Wage”: Naval Warfare and Finance in Archaic Eretria, in G. G. Fagan – M. Trundle, New Perspective on Ancient Warfare (2010) Leiden-Boston, Brill, 205-226.
 See Purpura, op. cit., pp. 536-537.
 W. Radcliffe, Fishing from the Earliest Times (1926) London, J. Murray, pp. 231–234.
 “Liberté des mers et territoire de pêche en droit grec,” Revue historique de droit français et étranger, no.55 (1977), p. 55.
 See C. Carusi, “Nuova edizione della homologia fra Trezene e Arsinoe (IG IV2, 76+77, IG IV 752),” Studi Ellenistici, no. 16 (2005), pp. 79–140.