Pulau Rupat is separated from the coast of Sumatera by Selat Rupat.
Foul ground, with numerous drying patches, extends about 7 miles offshore from the N side of Pulau Rupat and the NW side of Pulau Medang. A shoal with a depth of 14.7m lies 6.5 miles NNE of Tanjung Medang.
Between Tanjung Medang and Tanjung Mambul, the E entrance point of the N end of Selat Rupat, about 11 miles WSW, the tree-covered coast is bordered by a series of shoals which extend up to 5.2 miles offshore.
The NE side of Pulau Medang is tree covered and marked by some native villages. A conspicuous house with a red roof is situated about 4 miles SE of Tanjung Medang.
A detached bank, which dries on its outer side, lies about 2 miles offshore, about 6 miles SE of Tanjung Medang.