Sunda Strait
The strait between Java and Sumatra, its shoaling and currents, the traffic separation scheme in force from 2020, and why deep-draught traffic prefers Lombok.
The Sunda Strait separates Java from Sumatra and connects the Java Sea to the Indian Ocean. It is the shorter of the two archipelagic alternatives to the Strait of Malacca and the less used, because it is both narrower and shallower than the Lombok Strait .
The strait narrows to about 24 km at its northeastern end between Cape Tua on Sumatra and Cape Pujat on Java, and shoals there to about 20 m in parts, with strong tidal currents, sandbanks, offshore installations off the Java coast and the Anak Krakatau volcano. Those constraints together are why deep-draught operators route via Lombok when draught rules out a Malacca transit.
Sunda forms part of lane ALKI I in the partial system of Indonesian archipelagic sea lanes adopted by IMO resolution MSC.72(69) on 19 May 1998, so archipelagic sea lanes passage governs rather than transit passage. A traffic separation scheme was adopted on 10 June 2019 and entered into force on 1 July 2020, operated by Merak VTS. The full article will cover the bathymetry and its survey history, the currents, the volcanic and seismic hazard including the 1883 and 2018 events, and the ferry traffic crossing the shipping lanes.