Blowholes

What is blowhole?

The blowhole is an intermittent natural water fountain that is powered by wave energy. Visually it is quite similar to a geyser and often blowholes are just called – sea geysers. But the mechanism of blowholes is absolutely different. Geysers are created by thermodynamical factors (overheated water under less hot water in a narrow passage), but the fountains of blowholes are created by physical movements of the water – waves.

The term “blowhole” often is applied to several more exciting natural landmarks, such as the entrances in large caves where the air blows in or out. There exist also methane blowholes – craters that have been created by methane exhausts from the ground. This is an interesting and at the same time worrying phenomenon in the far northern lands: due to global warming there is thawing permafrost and in the atmosphere is released a huge amount of methane – a powerful greenhouse gas. Sometimes giant bubbles of this gas create enormous craters.

Wondermondo though includes on this page only the blowholes – water fountains. Here are included also other places where waves create interesting phenomena.

How do blowholes form?

The recipe for a proper blowhole – sea geyser – is as follows:

• There is needed a shore of the waterbody that is large enough for powerful and frequent waves – oceans and seas. Theoretically, this can be a large lake but thus far Wondermondo knows only blowholes in the oceans and seas.
• The shore needs to be “made” of sturdy, durable material. Blowholes in some respects are like guns – if the “barrel” is made of flimsy material, it bursts soon. The blowholes which are known to Wondermondo have formed in three kinds of rocks: limestone, basaltic lava, and granite. And even these materials are not durable enough – after some time the blowhole becomes too large and the fountains gradually disappear.
• There is needed a fracture or hole in the rock where the waves can enter… and retreat… and enter again. After some time wave energy creates a hole, then a cave, then an even larger cave. As the cave grows larger, with each wave more water enters it and leaves it creating higher and higher pressure differences in the cave.
• The pressure inevitably does what the pressure does best: it looks for weaker places and then breaks through. Such places are not downwards (there is even more rock) or sideways (again – rock). Thus: only upwards! Water finds a small fissure and gradually makes it wider. One day near the sea the rock starts beating a fountain after each wave. A blowhole is ready and served!
• Nothing lasts forever. As time goes on, the blowhole is eroded and becomes larger and larger. As a result, fountains become weaker and weaker. One day there is just a large hole with raving water on its bottom. Gradually the ceiling of the cave collapses. For a while there forms a nice natural bridge and then it collapses as well. A former sea cave with a blowhole has turned into a sea bay. But, most likely, nearby forms a new blowhole…

How high are the fountains of blowholes?

Nobody has measured, and, most likely, nobody has ever seen the world’s tallest fountains of blowholes: because nobody is there at the right time. It is well possible that the most powerful blowholes are found in remote areas and are active only during the most powerful storms. But we can be sure that the tallest fountains of blowholes are much taller than the world’s tallest waves and taller than any geyser in the world.

The height of the known blowhole fountains in most cases also is just… a guess. At least to some extent. We can compare the fountain with the height of nearby trees, cliffs, and other objects and say a rough number, e.g. – 30 meters. In reality, these could be 26 meters or maybe 40 meters. Who knows?

The tallest announced blowholes which are known to Wondermondo are:

• Thunder Bay Blowholes in Western Australia – they pass through 100 m tall cliffs and then create up to 20 m tall fountains!
• McSwyne’s Gun in Ireland. In the recent past, it was some 60 – 90 m high and could be heard more than 10 km far! Now it is also very impressive.
• Blaster Hole on the Horse of Copinsay in Orkney Islands, United Kingdom. Its water jets are up to 60 m high.
• Dirk Hartog Island Blowhole in Western Australia – up to 60 m high.
• Kiama Blowhole in New South Wales, Australia – sometimes also up to 60 m high.
• Tinian Blowhole in the Northern Mariana Islands – up to 60 m high.

Please, remember – these figures are just estimates by (mostly) unknown people.

How common are blowholes?

Most of the announced blowholes are located in touristy areas: Hawaii, Caribbean islands, Mexican coasts, and coasts of Australia. Other well-known blowholes are in areas with many nature and travel enthusiasts: Europe, Canada, the USA, and – also Australia.

Does it mean that blowholes are only there? Does it mean that there are no blowholes in less visited areas, e.g. the Kerguelen Islands or remote shores of Africa, or the Russian Far East? Most likely not: there should be many fine blowholes along these shores as well.

At the same time, this natural phenomenon is not very common. A proper blowhole requires a coincidence of several specific factors. Most likely there are several hundreds of locations on Earth with proper blowholes. Thus, if you happen to see one, even the most visited one (e.g. Kiama Blowhole or Nakalele Blowhole) – you are privileged to see a rare natural spectacle! Enjoy it!

Articles about blowholes: