A blowhole is a geological feature sometimes found along coastal regions. The phenomenon occurs when the tide fills underwater caverns with seawater.The caverns are caused by a geological process of shoreline erosion. This can happen through ‘hydraulic action’ where the waves cause pressure on the airpockets within the little cracks in the cliff, widening them further; ‘abrasion’ or ‘corrasion’ caused by the waves bashing rocks, pebbles, sand and other material into the cliff; chemical weathering caused by the acid content in seawater, especially lethal to rock compositions such as limestone; and ‘attrition’, a sandpapering effect caused by small loose circular rock debris. If the caverns have an aboveground opening; the pressure causes the water to push out periodically in a fountain, or ‘blow’. The timing and height of the water fountains from these blowholes are dependent on the tides and wave formations.
Whilst there are many blowholes all over the world, and especially along the European coast; Sri Lanka only has one known blowhole. It’s near Kudawella, a small fishing village in the Southern Province. Hummanaya can be reached by crossing over a tombolo; a piece of land that is created when deposition of sand or gravel occurs, connecting an island to the mainland.
This blowhole has achieved fame amongst visitors to the island, as it is believed to the second largest blowhole around the world. Named after the strong humming sound that it produces while active; Hummanaya Blowhole can shoot up to a height between 25 – 30m.
Please note that it’s not accessible by wheelchair, due to a flight of stairs that have to be taken.