Under the sea (ice)

Contrary to what the title may imply, I did not fall through the sea ice and go for a swim. I did, however, get to go for a view of McMurdo sound under the sea ice. Each year, there are a number of research projects going on that focus on the aquatic life. Dive teams regularly go diving under the ice, which sounds freakishly dangerous but they've all said it's the easiest diving they have ever done. This is typically done using diving huts that they drag out onto the sea ice and place over holes they've drilled in the ice.

Looking at the sea floor through the bottom of the dive hut. A concrete block can be seen, as well as sponges and other assorted sea life (white spots).

The dive teams typically go out once a day and go diving for 30 minutes to an hour each time. I happened to be out there when a group of artists were preparing to dive under the ice to do sketches of some of the different sea life.

Divers prepare to enter the water.

So how did I get a view under the sea ice? Each year in November, they install the Observation Tube (or "Ob Tube") in the ice. They drill a large hole in the sea ice and drop in the tube, which is basically a long vertical pipe with rungs. At the bottom is a glass observation pod where you can view the ocean under the sea ice.

Looking down the Ob Tube.

The tube itself is pretty confining, as is the pod at the bottom. Only one person at a time can go down and if you are claustrophobic, this is not the activity for you. Before they open the Ob Tube to the general McMurdo populace, the fire department has to hold drills every year so they know how to get people out if they get stuck (which does happen with some frequency apparently). Anyone taller than 5'11" also has to be able to raise and lower themselves using just their arms because the tube is so narrow, you can't bend your legs enough to get your feet on the rungs as you climb or descend. Once you climb down, there is a small box at the bottom of the ladder that you can sit on. The views were simply breathtaking. Beautiful greens and blues surround you, and you can see the land sloping away into the depths below.

While this picture doesn't do it justice, here's a pretty good idea of what it looks like under the sea ice. The "line" you can see is likely a small pressure ridge that has formed.

You can see all manner of sea creatures, from tiny fish to Jellies to the occasional seal or penguin that might come swimming by. Unfortunately, I only saw the small fish. I was surprised that the bottom of the ice was not white or blue or green, but rather had a yellowish hue. Algae actually thrives on the bottom of the sea ice, covering it as far as the eye could see. This is likely a major food source for some of the aquatic life.

But it's not just the sights that make this experience unique, it's also the sounds. You can hear every noise under the water, including the seals as they talk to each other. In most cases, you may not see the seals at all, but you can still hear them talking even from great distances. I might have caught some on my GoPro, but I'm not entirely certain and will need to check when I get home.

Another feature they have added this year is a semi-permanent underwater video camera that will be recording the sea floor for the entire next year. The scientists on this project hope to be able to see how the sea floor changes from summer to winter as far as the variety of sea life.

You can see the cable going down to the web cam on the sea surface. A faint ice stalactite can also be seen on the bottom of the ice just to the left of the cable.

View of the video camera on the sea floor.

One interesting thing to note regarding the Ob Tube is that the temperature in the tube is typically warmer than the air above the surface. The sea temperature is at or just below freezing while the air temperatures this day were in the teens, which meant the Ob Tube and the air in it were warmer than outside (especially with no wind). Ice can still form in the ocean water though and I got a picture of ice beginning to form on the outside of one of the Ob Tube windows.

Ice forming outside one of the Ob Tube windows in an intricate feather-like pattern.

Overall, this ranks as one of the most interesting things to do around McMurdo and certainly helps engage the general populace and get them excited about some of the science that is happening.