Several narrow banks lying in a N to S direction, with depths of 1.2 to 5.5m lie in the N part of Selat Kungkung.
Selat Kungkung, entered between Pulau Merbau and the W end of Pulau Rangsang, should not be used by vessels without local knowledge, as the approaches for 20 miles to the N are fouled by long shoal ridges some of which have depths of less than 1.2m and they are not buoyed.
A drying bank extends up to 1 mile from the NW coast of Pulau Rangsang.
At Tanjung Majan, about 7 miles E of Tanjung Ajung, Selat Kungkung leads into Selat Ajer Hitam, which separates Pulau Rangsang from the N side of Pulau Tebing Tinggi.
In Selat Kungkung and Selat Ajer Hitam, the SE currentstarts about 2 hours after LW, and the NW current about 2 hours after HW, at rates of 2.5 and 4 knots, respectively, at springs. Both currents are weak at neaps, the NW current being the stronger.