Watch: Inside the World's Longest Sea Caves | Expedition Raw

Okay, let's go for it.

I actually went to New Zealand to study the other side of the island. But to satisfy my curiosity, I started exploring this coastline, and that turned out to be the day that I actually discovered the longest sea cave in the world. On this coastline, that's only about a mile long, it contains six of the ten longest sea caves in the world, including the two longest.

It's really exciting. You get to an entrance, and you really have no idea what's going to happen. Pushing down that next passage, maybe the swell is sort of cresting up to the ceiling, and you might have to hold your breath just to go through to the next part. You don't know if that's the end of the cave or if it's going to open up into a big room full of beautiful formations or interesting sea life.

These caves have some really impressive cave formations in them that, as they slowly drip, record climate through time just like tree rings do. It's one small piece of the global climate puzzle. Then we can start looking at things like what's the erosion rate because the way sea caves form is by eroding coastlines.

We're mapping these caves using both traditional 2D cave survey and also newer three-dimensional surveying based on photography. We can get texture on the cave walls of all these features in addition to the shape and morphology of the cave. But we still have a lot of work to do because with caves, you truly don't know what you're getting yourself into until you get yourself into them. It's true exploration.