In the last March, we went to Langkawi Island. We had the opportunity to have a boat trip touring Kilim river from Kilim jetty, at the north eastern edge of Langkawi, up to the estuary heading to Andaman Sea. It was a fascinating trip, entertaining and educating for not only the kids but us too. It took about three hours in one afternoon.
The best parts were seeing the green mangrove forests, caves, as well as the peoples living in the area
Here is video collecting photos there uploaded by Farhan at his page.