I’ve always thought that the Halona Blowhole, and blowholes in general, are very unfortunately named. They should instead be called ocean geysers or lava tube spouts – but blowhole? Really? Oh well, there’s nothing I can do about it. The unfortunate name doesn’t change the fact that the Halona Blowhole is one of Oahu’s most exciting natural wonders. Like Diamond Head– people come to Hawaii with seeing ‘the blowhole’ on their bucket list – often without knowing what to expect.
Halona is a stretch of rocky and wild coastline on the South shore of Oahu. The word Halona means overlook in Hawaiian language and as descriptions go, it’s pretty apt. Sitting between Breakneck Beach (Sandys) and Hanauma Bay – this rocky overlook provides views of whales, Maui, multi-colored water, and of course, the aforementioned blowhole. So, just what is the blowhole?
Several hundred thousand years ago, the Koko Head volcano was active and lava flowed from it to the ocean below. Surface lava cooled quickly and hardened into stone, but under the surface rivers and streams of molten rock made their way to the ocean. As the streams dried up, they left tubes behind – sometimes large, other times small. Most of them collapsed from the weight of the rock above but some of them (in particular smaller ones) remained as small tunnels. One such lava tube formed at Halona and was left just below the high water mark. Tens of thousands of years of wave action eventually broke the surface of the tube so that incoming waves would burst through the rock after traveling some distance in the lava tube – if the pressure was (or is) strong enough based on direction of the waves, volume of water, and tidal conditions – the water spouts skywards and sometimes causes visitors to get wet!
On the right day, at the right time, in the right conditions – the Halona Blowhole goes as high as 30 feet! Other days you are lucky to see a little mist coming out. Nearly every visitor to Oahu makes the trek to Halona – the parking lot can be crowded – but on the right days – you won’t even notice the people. Don’t forget to look behind you at the Kokohead Volcano. 
There are strict rules in place and visitors are not allowed to go down to where the blowhole erupts. In the past there were no fences or barriers and adventure seekers would get close to the blowhole to feel the power of nature…and some of them died. There have been a handful of fatalities from people making bad decisions and the result is that no one is allowed to go near the blowhole. On one tragic day, a teenager got blasted by the spray and then sucked into the blowhole and died in front of visitors.
The Halona Blowhole parking lot is also where you park if you want to visit Eternity Beach – but I’ll tell you about that in another post.