Sri Lanka Rivers?

Hi guys,

new on here, planning a trip to Sri Lanka for vacation, currently pondering if I should bring the packraft for some excursions.
Looks like most rivers are smooth and easy to navigate.
I see many tour operators offering kayak trips with simple sit-on kayaks, so it should be more than manageable.

Though I don’t find much info regarding permits or other folks that did it on their own.

Anyone has experience or a contact to turn to?

Thank you so much!