Rikoriko Cave
Rikoriko is Māori for “waning light” or “twilight,”
Referring to the shimmering patterns created by sunlight reflecting off the water onto the cave’s walls and ceiling. Repeating a word in Maori can intensify the meaning or it can show that the action is continuous or repeating.
The affects of the light are best viewed when the sun is lower in the sky during the morning or afternoon. In the winter, the light can be seen to dance on the walls at the back of the cave as the light reflects of of the waters surface.
As you head back out towards the entrance, look at the cobalt blue water and the shimmering light on the walls before you leave.
Cave formation
The cave is believed to have been formed 10–15 million years ago by a giant gas bubble from a volcanic eruption, which was later breached and enlarged by sea erosion.
Life in the cave
Above the cave is around 100 metres of volcanic rock. Look up and you may feel water drop onto your face. This is rain water that has passed through the vegetation above, then been filtered through the rocks until it falls back into the sea. You will also notice on the ceiling, greenery. This is a mixture of mosses and ferns. They cling to the rocks and survive on the water that passes through the rocks above. But for a plant to survive, photosynthesis must take place. And for this they require sunlight, this they collect from the sunlight bouncing off of the waters surface and reflections reaching the ceiling.
Below the water is just as interesting due to the lack of direct light. As you travel underwater towards the back of the cave, the light diminishes. This represents the vertical journey into the depths of the ocean. So as you go towards the back of the cave, you start to see sponges and other invertebrates that you would normally only find at over 80 metres and deeper in the ocean. And due to these sponges, the water in the cave is usually pretty clear.
Largest measured sea cave – in the world
Measured at approximately 130 metres long and 80 metres wide, with a ceiling reaching 35 metres high. So of this is of course underwater.
Using a sophisticated 3D laser scanner for the above water section of the cave, and traditional hydrographic surveying techniques for the seafloor, above and below water models were calculated for a combined volume
The back of the cave is around 8 metres deep and the entrance is over 20 metres deep. Outside the cave the seafloor gently slopes away to well over 40 metres.
The cave has a calculated volume of 221,494 cubic metres.
The shape of the inside is quite rounded and so this lends itself to some amazing acoustic quality when the sea is calm and the boats have their engines turned off. An echo was once recorded to last 14 seconds in the cave. Many visitors enjoy a sing, a whistle or even to play an instrument to experience the acoustic during their visit. Many a Happy Birthday have been sung there.
According to one sound engineer, the acoustics in the cave rival that of the Sydney Opera House and Taj Mahal.
The cave has received some musical talents over the years; Neil Finn: Performed a concert inside the cave, utilizing its unique, echo-heavy, and resonant acoustic qualities.
Troy Kingi: Performed a song in the cave, which is considered a sacred, spiritual, and special place by many visitors.
Dame Kiri Te Kanawa & Split Enz: Reportedly sang in the cave.
The cave has also hosted New Year’s parties, often featuring music from our friend DJs like Gareth-B.
When we visit our guests may be lucky to hear our skippers murder, I mean play a “authentic/traditional” maori horn or flute.
Fun facts
Dead Whale
In 2010, the carcass of a 15-metre sperm whale carcass washed into Rikoriko Cave. It become so smelly the sharks stopped eating it and Department Of Conservation decided to tow it out of the cave and dump it over deep water. As they removed it, parts started to break off. At the back of the cave under the arch in 8 metres of water, still lays a jaw bone. Another is out in close to 40 metres at the entrance. The one in the cave looks white and clean, like pumice stone. The one outside is overgrown and hard to recognise.
World War II
In the Second World War, it is reported that a Japanese submarine tucked away inside the cave and stopped for two weeks whilst undergoing repairs. Whilst there is no documented evidence, there was certainly german activity in the area with the laying of land mines around the Hauraki Gulf by German auxiliary cruiser HKS Orion to disrupt Allied shipping. Two of these mines claimed New Zealand vessels; The Niagara, which was carrying British gold to the US to pay for the war efforts. And the Pururi, ironically a 57 metre, twin diesel New Zealand Mine Sweeper who struck a mine on 13th May 1941 that it was looking for off of Bream Head.
Ready for take off
One verbal report tells of a homemade amphibious microlite being in the cave. Manoeuvring the aircraft to the very back, it attempted to get airborne by the time it reached the entrance of the cave. According to the report, it was successful.
