As seen at that previous blog entry and as germane to the topic the movement of a Chinese nuclear submarine through the Strait of Malacca:
"The submarine [Chinese] was later seen crossing the Malacca Straits in June 2016 [moving from west to east?].. Submarines have to surface while crossing straits as per protocol."
That protocol having a basis in law and regulation to include the movements of submarines!
"Chapter IV International Straits by Lewis M. Alexander The Law of Naval Operations"
1. The Transit Passage Regime
"There are a few carefully-phrased exceptions in the Convention to the transit passage provision, as noted below. Passage of ships and aircraft is to take plane in the 'normal modes' of transit, a term which the United States interprets as meaning that submarines may transit submerged, providing that depths in the strait are sufficient to permit such operations."
NO WHERE in the Safe Passage rule book for mariners making passage through the Strait of Malacca can I find any reference to military vessels. Warships must pass through the strait on the service and this well understood, the area constricted, shallow and having heavy surface traffic.
"The maximum size of a vessel that can pass through the Strait is referred to as Malaccamax. For some of the world's largest ships (mostly oil tankers), the Strait's minimum depth (25 metres or 82 feet) isn't deep enough. In addition, the next closest passageway (the Sunda Strait between Sumatra and Java) is even more shallow and narrow than Malacca. Therefore, these large ships must detour several thousand miles/kilometers and use the Lombok Strait, Makassar Strait, Sibutu Passage, or Mindoro Strait instead."
* Sunda Strait . . . "the strait between the Indonesian islands of Java and Sumatra. It connects the Java Sea to the Indian Ocean."
* Lombok Strait . . . "a strait connecting the Java Sea to the Indian Ocean, and is located between the islands of Bali and Lombok in Indonesia,"
* Makassar Strait . . . "a strait between the islands of Borneo and Sulawesi in Indonesia."
* Sibutu Passage . . . "a deep channel some 18 miles (29 km) wide that separates Borneo from the Sulu Archipelago"
* Mindoro Strait . . . "one of the straits connecting the South China Sea with the Sulu Sea"
South China Sea naval choke points and more.Choke points for egress to the Pacific Ocean also shown.
Correct! A Chinese submarine making passage from a home port through the South China Sea into the Indian Ocean via the Strait of Malacca [and return] NOT having an alternative but to use other oceanic choke points that require a voyage of "several thousand of miles/kilometers" ADDITIONALLY!
Stealthiness of the submarine negated by the constricted and shallow waters of each choke point.
This is a problem for the Chinese submariner operating in the Indian Ocean there apparently being no amelioration?