Longest sea cave
- Who
- Matainaka Cave
- What
- 1.54 kilometre(s)
- Where
- New Zealand
- When
- October 2012
The longest cave in the world formed by wave action from the sea is Matainaka Cave on New Zealand’s South Island. Surveys completed in October 2012 established its total length as 1.54 km. The cave is still forming and growing gradually longer.