Hummanaya
Hummanaya Blowhole is the only known blowhole in Sri Lanka and it is considered to be the second largest blowhole in the world. (Sinhala:  = ) refers to the noise, "hoo", that can be heard a distance away when the blowhole is active. Location
The Hummanaya Blowhole is located  from the small fishing village of Kudawella, which is  from Matara,  from Dikwella and  from Tangalle, in the Southern Province. Attraction
Hummanaya is a natural blowhole and is caused when sea water rushes through a submerged cavern and is pushed upwards. The sea water flows underneath the shore and then comes out of this hole due to pressure. The water fountain created by the geological feature shoots up every couple of minutes, depending on the nature of the sea, with the spray often reaching as high as  to . This site has now been developed as a tourist attraction, with a small visitors' information centre on marine life and a viewing platform. References

Blowholes
Tangalle