One of the reasons to creation of hot spring is igneous activation. Igneous actions mainly occur in between plated margins in the earth crust. Sri Lanka is situated in Indo-Australian plate out of other seven plate named as African, Pacific, Antarctic, Eurasian, South American, North American and not close to the plate margin.
So the island has no any active volcanoes. But there are 12 well recognized hot springs in Sri Lanka. Sri Lankan earth crust has categorized in geography in three major plates named as Wanni complex, Highland complex, Vijayan complex.
Most of the hot springs is situated in a line from Hambanthota to Trincomale between so called Highland complex and Vijayan complex. Those are namely Rankiriya and Kinniya in trincomale district, Madawawa, Borawawa, Mutugalwela and Gurukubura in Maduruoya national park in Polonnaruwa district, and Mahaoya, Wahawa. Kapuralla, Emmbilinne in Ampara district, Madunagala in Hambanthota district.
One hot spring is in the Wanni complex in Jaffna peninsula at Keerimalai, a large,
walled-in, sunken bath a few steps off the beach was discovered in
Punithanagar near Katkovalam, in Vadamaradchi East in the Jaffna district ...
All the hot springs are suitable for bath with a bucket out of Wahawa hot water tube well which water fall on to head continuously from height about 12 feet. Kinniya, Mahaoya, Madunagala hot springs are well constructed as bathing spots by local councils and have to pay for a ticket. In our round tours we try our best to bath you at hot springs.