Sirene Reefs, one of the outermost dangers in this locality, consist of four heads, of which the westernmost and the southernmost, with 0.9m of water, sometimes break; there are depths of 1.4 and 6.9m on the other two patches.
Pulau Tamang (Pulau Temang) is an easily-identified hilly island (Area:10Km²with an average elevation of 1 m above the sea) located at the SE extremityof Teluk Batahan, about 1 mile from the coast. It is fringed by areef except at its W end, where there is a depth of 11m ...
The coast between Tanjung Tabujung and Ujung Sikarakar, about 14 miles S, is fronted by many dangers, some of which lie just within the 10m curve. Natal Road that lies off the coast between Ujung Sikarakara and Ujung Rakat, about 6 miles S, is open W and is encumbered with many ...
An above-water rock lies about 1 mile offshore, 14 miles N of Tanjung Tabujung. Tabujung Road, located N of Tanjung Tabujung, is partly sheltered by Pulau Tangah (Pulau Tonga) and Pulau Si Dakah (Pulau Labu, about 4 and 1.5 miles, respectively, NW of Tanjung Tabujung.
Karang Posumah consists of two patches, located about 7 miles ENE and E, respectively, of Pulau Bodjo; they have depths of 4.9 to 5.5m. The SW side of the bank is very steep-to, but the NE side is more shelving. The shallowest parts may occasionally be distinguished by the swell, ...
Gosong Makasar (Makasser Reef), with a depth of 0.6m, lies about 12 miles SSE of the S extremity of Pulau Bodjo. It is easily recognized in the daytime by the high breakers on its shallow portion. The reef extends 1 mile beyond the breakers.
The coastal plain between the Sungai Singkil and Udjung Tuan, about 156 miles SE, is generally narrow, being backed by mountains with numerous peaks. 
