Tidal currents are strong in the river and only small craft with local knowledge should attempt to enter.
Between Kuala Bernam and Kuala Selangor, about 39 miles SE, the coast is low and fringed with mangroves. The mud banks fronting the coast extend for less than 0.5 mile until within 5 miles of Kuala Selangor where they extend for a distance of 2 miles.
A chain of shoals with depths of less than 5.5m lies 5 to 7 miles offshore about midway between Tanjong Sauh and Kuala Selangor. A spit with depths of less than 5.5m, bank off Kuala Selangor, extending towards the chain of shoals described above.
Enclosures for catching fish are situated off and along the coast a few miles apart. They are generally found in depths up to 11m and are therefore useful in defining the shallow water.