Cathedral of the deep

"And it's peaceful in the deep
Cathedral where you cannot breathe
No need to pray, no need to speak
Now I am under all...
And the arms of the ocean are carrying me
And all this devotion is rushing out of me
And the crashes are heaven for a sinner like me
But the arms of the ocean delivered me"
- "Never let me go" by Florence and the Machine

I love diving under the WHOI pier. It's where I've done most of my training dives, and it is heaven for a benthic ecologist. The pier is supported by a series of pilings, all of which are inhabited by invertebrates. Sponges and anemones and ascidians of all kinds. It's goregous.

Benthic fauna on the side of the instrument well

We always start dives from the instrument well. It's a rectangular opening in the pier, sheltered from waves and boat wake. We jump into the water from the side of the well and then grab hold of a descent line - just a vertically-hanging rope that leads to the bottom. The line actually follows one of the pilings, so I get a full depth profile of the fauna every time I swim down or up. From the surface down to about 9 m (30 ft), the most common organisms are Styela, a club-shaped solitary ascidian, and Didemnum vexillum, a peach-colored invasive, colonial ascidian. In fact, most Styela are covered in Didemnum. You can see the peach-colored, club-shaped forms just below the water line in the photo at right. Below about 9 m, though, those two species disappear and are replaced by small red anemones and a yellow sponge. On the seafloor itself, large flounder, massive conchs, and the common sea star Asterias rubens dominate.

Once we reach the bottom of the descent line, we are free to swim under the pier. It's hollow down there, and the water is interrupted only by the pilings and a few random objects. There are guide lines connecting the pilings, so in case you get lost, you can follow the lines back to the instrument well. The random objects on the seafloor can be used for orientation, too. For example, a lobster trap and an ammunition box rest on the sand just west of the descent line, and an old cart lies to the south of it. A pipe on the seafloor marks the edge of the pier, and if you reach the fake plastic hawk, you've gone too far. Everything is covered in benthic fauna, but still the pilings are my favorite.

Pilings supporting the WHOI pier

In a way, the pier reminds me of a cathedral. The pilings are the pillars holding up the grand vaulted ceiling. Every surface is covered in elaborate designs. It is peaceful, quiet, and meditative. When diving, you actually have a reflexive response that causes you to calm down. It's called the Mammalian Diving Reflex, and everyone from humans to whales do it. When your face is underwater, your heart rate slows, your peripheral blood vessels constrict, and your breaths naturally lengthen. To me, there is nothing better than being underwater, breathing slowly, swimming gracefully, surveying benthic fauna. It is relaxing and scientific and wonderful.