[This article has since been updated to incorporate information from user comments]
Yesterday morning I was shocked to hear about the attack by Israel on the Mavi Marmara, a civilian ship carrying humanitarian aid to Gaza. In the ensuing bloodbath 10 civilians were killed by Israeli special forces. All over the web it was reported that the ship was attacked in international waters. This is a crucially important and surprising fragment of information, but is reported widely enough to be credible: use of the term “international waters” occur on the sites of the New York Times, pravda.ru, Asia Times Online, The Guardian, the Washington Post, to name a few.
To attack a foreign flagged vessel in international waters is illegal. It is not piracy, as the Israeli vessels carried a military commission. It is rather an act of illegal warfare. This seems like a really stupid thing for Israel to do. Even if you discount the morality (or lack thereof) of attacking an aid convoy, surely they risk the wrath of the world for flouting international law? Turkey’s minister of foreign affairs, Ahmet Davutoglu, is on record calling this incident “tantamount to banditry and piracy; it is murder conducted by a state.”
But where are these “international waters” which Israel violated, exactly? I googled it, and it is surprisingly hard to find a good definition. Wikipedia has a nice article and coloured world map showing international waters (a.k.a. the High Seas). International water (where no country has any claim whatsoever) generally starts 200 nautical miles (370 km) offshore, but the Mavi Marmara seem to have been intercepted a mere 150km offshore (falling in Israel’s exclusive economic zone)
According to this map there are no international waters in the Mediterranean Sea! Every square inch of it seems to belong the the surrounding coastal states.

But where are the International waters where Israel stormed the ship? Turns out this map doesn't show the whole truth - see below.
So, if there are no international water in the Mediterranean, in which water did this attack take place? If not Israeli waters, then maybe in those of Egypt or Cyprus? But why then not say so directly? Or is this merely a term parroted by all the news sources to make the story sound more dramatic and controversial?
Turns out that all those news sources are right – the exclusive economic zone, although not completely neutral in terms of economic rights, cannot be enforced by the national laws of the coastal state, as stipulated in the United Nations Convention on the Law of the Sea.
However, this is not only about transgressing territorial waters, but about running a blockade. A blockade is a recognized legal construct, and must be formally declared (it was), for a plausible reason (Israel gave one), and be effectively enforced (it is). But, the quarantined area may not extend too far beyond the coast, although the law isn’t specific on distance. (Many scholars interpret the language of the London Declaration to limit blockades to the standard 12 nautical miles that define territorial waters.) A longer discussion on the blockade’s legal status can be found here.
Therefore Israel’s violent “defence” of the blockade is built on shaky (international) ground.


You must have noticed the Wikipedia statement that the source is only a single source and needs further support.
Secondly, your research was incomplete. I wonder why. Wikipedia defines Territorial waters, or a territorial sea, as defined by the 1982 United Nations Convention on the Law of the Sea[1], is a belt of coastal waters extending at most twelve nautical miles from the baseline (usually the mean low-water mark) of a coastal state. The territorial sea is regarded as the sovereign territory of the state, although foreign ships (both military and civilian) are allowed innocent passage through it; this sovereignty also extends to the airspace over and seabed below.
The term “territorial waters” is also sometimes used informally to describe any area of water over which a state has jurisdiction, including internal waters, the contiguous zone, the exclusive economic zone and potentially the continental shelf.
What you describe is referred to as Exclusive economic zone:
An exclusive economic zone extends from the outer limit of the territorial sea to a maximum of 200 nautical miles (370.4 km) from the territorial sea baseline, thus it includes the contiguous zone.[3] A coastal nation has control of all economic resources within its exclusive economic zone, including fishing, mining, oil exploration, and any pollution of those resources. However, it cannot prohibit passage or loitering above, on, or under the surface of the sea that is in compliance with the laws and regulations adopted by the coastal State in accordance with the provisions of the UN Convention, within that portion of its exclusive economic zone beyond its territorial sea.
Before 1982, coastal nations arbitrarily extended their territorial waters in an effort to control activities which are now regulated by the exclusive economic zone, such as offshore oil exploration or fishing rights (see Cod Wars). Indeed, the exclusive economic zone is still popularly, though erroneously, called a coastal nation’s territorial waters.
Source: http://en.wikipedia.org/wiki/Territorial_waters
ATW