Record #00415Nature archive
Riko Riko Cave in New Zealand's Poor Knights Islands has a measured total cavity volume of 221,494 cubic metres and was long cited as the world's largest sea cave by volume. A 2024 three-dimensional survey of Klæmintsgjógv in the Faroe Islands reported a larger space, placing the current record holder in dispute.
Current Record
about221,494m³
Current record value
Disagreement and differing conclusions：Riko Riko's 221,494 m³ is a supported survey value, but its claim to remain the current world's largest has been challenged by newer measurement. The roughly 227,000 m³ Faroese figure is air-only, not the complete air-plus-water volume; published Faroese total estimates vary. The historical and current record holders should not be assumed identical.
View verification detailsRiko Riko Cave lies within New Zealand's Poor Knights Islands. A speleological account by Dave Bunnell documents surveyor Jeremy Elrick's combination of terrestrial 3D laser scanning and underwater echo sounding. The measured total cavity volume was 221,494 m³, with about 42.5% below water and an uncertainty estimated at 4.5%.
The study describes maximum cave dimensions of about 153 metres long, 96 metres wide and 38.1 metres high. The island's volcanic rocks contain joints and fractures susceptible to marine erosion. A proposed origin as a trapped gas bubble in cooling lava was presented as local speculation, not a verified geological conclusion.
In 2024 the surveying company Emesent reported approximately 227,000 m³ of airspace alone for Klæmintsgjógv on Hestur in the Faroe Islands, with another roughly 50,000 m³ underwater still pending confirmation in its report. Faroese tourism material also calls it the largest sea cave, although published estimates vary; Riko Riko therefore should not be presented unconditionally as the current world-record holder.
There is a documented substantive disagreement about measurement, comparison boundaries or the record conclusion.
Basis: documented substantive disagreement
NCKRI's Sea Caves page still lists New Zealand's Riko Riko Cave as the world's largest by volume at 221,494 m³, supported by Dave Bunnell's specialist report on Jeremy Elrick's laser/echo-sounding survey, which reports 4.5% uncertainty. A 2024 firsthand Emesent LiDAR study of Klæmintsgjógv reports around 227,000 m³ of airspace alone, above Riko Riko's cited total air-plus-water estimate. At the time of that report, an additional ~50,000 m³ underwater awaited hydrographic confirmation. Faroe Islands tourism pages also claim the current largest sea cave. The competing published claims are disclosed without treating an unreconciled ranking as definitive.
Riko Riko's 221,494 m³ is a supported survey value, but its claim to remain the current world's largest has been challenged by newer measurement. The roughly 227,000 m³ Faroese figure is air-only, not the complete air-plus-water volume; published Faroese total estimates vary. The historical and current record holders should not be assumed identical.
National Cave and Karst Research Institute
The world’s largest sea cave by volume is Riko Riko Cave
Cave Types, Sea Caves section
National Speleological Society / Dave Bunnell
a volume of 221, 494 cubic meters
Riko Riko Cave, THE SURVEY section
Current Entry identifies the current entry in this archive; it does not establish that the record is still held today.
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