Question: how did you feel the first time you went deepsea and saw the underwater volcanoes?

Jon Copley answered on 13 Jun 2010:

It was the most exciting eight hours of my life (and I’ve not led a dull life either!). The first time I dived in a minisub was with the US Navy, and we went to undersea volcanic vents one-and-a-half miles deep in the Pacific.

The minisub that we used only takes three people: the pilot, co-pilot, and scientist. It’s very cramped – the inside of the sub is just six feet across, so you can reach out and touch both sides. It is also cold – normal deep-sea temperature is just 2 degrees C, and the sub is basically a hollow metal ball, so it loses heat rapidly and you have to wrap up warm.

This particular sub had three small portholes to look out of (one for the pilot, one for the co-pilot, and one for the scientist). The portholes have to be small to withstand the huge pressure at the ocean floor. My nose was pressed up against the porthole for the whole dive, because I didn’t want to miss a glimpse of anything.

During descent it is dark – sunlight fades out by about a quarter-mile deep, and we keep the lights off until we arrive at the ocean floor to save battery power. But you can see flashes of light, called bioluminescence, created by deep-sea creatures – and it’s fun to play “join the dots” to imagine what creature is behind each light show.

Once we arrived at the bottom and switched on the lights, I was stunned by the alien-looking landscape stretching out into the darkness away from us. We were diving on a chain of undersea volcanoes, so we were flying over lava flows that had solidified into weird shapes – not like any landscape on land. In some places the lava looked like twisted ropes laid out across the seafloor, in others it looked like someone had squeezed the lava out of a toothpaste tube as it solidified.

What struck me most was that we were the first people ever to see this particular part of our planet. Although there had been a couple of dives in the area already, we landed off the map (and spent some time driving around to figure out where we were!). No-one had ever seen the underwater cliffs and canyons that we crossed.

At one point a fish called a “chimera” was hanging just the other side of my porthole, about three feet away from me, yet a world apart. There we were in a titanium-encased bubble of light, air and warmth, while the chimera fish lives in a realm of darkness (apart from bioluminescence), cold, and crushing pressure. And yet it was looking in on us with one of its big bioluminescence-detecting eyes, as I was looking out at it. I’ll never forget that moment.

Eventually, after three hours on the ocean floor, we found the undersea volcanic vents that we were looking for. But the robotic arm on the front of the sub developed a fault, so we couldn’t collect all the samples that we were supposed to on that dive. I was keen to stay on the ocean floor to do some more exploring, but we were ordered back to the surface so the sub could be fixed (absolutely the right decision, but I just didn’t want to leave!).