Do you remember when earlier this year James Cameron (of Titanic and Avatar fame) released a 3D movie called Sanctum? It didn’t get a lot of critical acclaim, and it wasn’t around for very long, so I don’t blame you if you missed it. One thing it did do quite well was show some beautiful cave images, and raise some interesting questions about cave diving and photography. National Geographic took the lead on setting the record straight by interviewing photographer Stephen Alvarez, a cave expert, about what it’s really like to explore—and photograph—in these treacherous locations far underground. You can watch the movie trailer and read the interesting interview at National Geographic’s Blog Central.