Just like the actual hike, the directions to get to the trailhead is very simple. You can check out the Trail Map to see its location as well.
As you drive through Castara on the Northside Road, you will see a recreational ground opposite the Castara Government Primary School. The field is bordered by the Castara River on one side and a road on the other. That road is River Road and its entrance is shown below.
on River Road
next to the field and walk across it to the river. The trailhead is located at the top of the field next to the river as shown in the following picture.
The trail then follows the river upstream to the waterfall.