To get to Kaikoura, Clyde Roper and his American colleagues ventured around the world to the city of Christchurch in New Zealand, that two-island nation near the bottom of the globe. The jumping-off point for Antarctica, Christchurch lies along the east coast of New Zealand’s South Island. About 93 miles (150 kilometers) north of Christchurch, up a rumpled coast, is the Kaikoura Peninsula, the gateway to the abyss known as Kaikoura Canyon.

The expedition is exploring the canyon with equipment designed to see and hear what is happening in a strange oceanic world as unexplored as the far side of the moon.