Clay canyons

I have dived in six continents and about 1030 dives. One of the best ones ever was a dive I did in August 2014 when we first found the clay labyrinth from Simo with my colleagues from Metsähallitus.

It was a late afternoon or early evening on an extremely beautiful summer day, calm and warm, almost tropical. Me and Niina were in one boat and we’d just send a text message to the other boat that we would just do a couple of drop videos more and then drive back to Ulkokrunni island to stay for the night.

Niina was driving, I was watching the water from the bow when suddenly I saw these dark features under the calm surface. They looked like canyons of bedrock, but in the northern Bothnian Bay, the bedrock is almost always under meters thick layer of till (moraine). It had to be something else. We lowered a video camera and looked in amazement when canyons and labyrinths of clay unfolded on the screen, under us.

Clay canyon under water.
Clay wall in the clay labyrinth. Photo by Janni Ketola, Metsähallitus.

We put down a 100 m transect line and I prepared to go for a dive (at that time, we could still dive in two persons teams, later it was decided that at least 3 people are needed on a dive team). I went to the bottom and couldn’t believe my eyes! I arrived in a middle of a labyrinth of clay canyons, gorges, craters and walls. There was a 1-1,5 m thick layer of hard clay on top of a beautiful wavy sandy bottom at about 4-4,5 m of water, and I spent the first half of the dive just exploring this weird and alien landscape. I had never seen anything like that before, and I just didn’t want to get out and back to the surface.

Clay canyon looks like a path with walls on both side.
Sandy bottom and clay on each side. Photo by Essi Keskinen, Metsähallitus.

It was amazing how the underwater nature was taking the hard clay. There were vascular plants like Potamogeton perfoliatus and greel algae like Charales which attached to the clay with their roots and rhitzoids like it was soft bottom. On the other hand, there were creatures like the sponge animal Ephydatia fluviatilis, which took the clay to be hard bottom and happily grew there.

For me, it was probably the highlight of my dives as a Metsähallitus marine biologist.

Written by Essi Keskinen, Metsähallitus

Diver on the water. Ready to take samples on sample tubes.
Diver with clay on the background. Photo by Janni Ketola, Metsähallitus.

“Metsähallitus SEAmBOTH-team got a tip from a local diver about a clay area between Ulkokrunni and Maakrunni about one year ago. On 7th of August 2019 our field team first took drop-videos of the area, and after finding clay, we made a transect line. Me and Eveliina went down to the bottom and first we found just sand and gravel. But after 10 minutes or so, there was a beautiful “clay wall” on our right side! After that there was clay almost everywhere and we had an amazing dive there.” -Suvi Saarnio, Metsähallitus

First encounter with the clay wall! Video by Eveliina Lampinen, Metsähallitus.
Diver under water, above a transect line.
Diver taking a sample from the clay canyon. Photo by Eveliina Lampinen, Metsähallitus.
Upper part of the clay canyon. Video by Suvi Saarnio, Metsähallitus.

“On 8th of August our team joined forces with the Geological Survey of Finland and took samples from a clay labyrinth that Essi & Niina found in 2014 from Simo (see above). Geological Survey of Finland is analyzing the samples taken from both the clay labyrinth in Simo and the clay canyon in Ii (Ulkokrunni) and we should know more about these features soon!” -Suvi Saarnio, Metsähallitus

Sea surface with small waves, bottom visible. Picture from up in the air, straight downwards.
Clay labyrinth easily visible to a naked eye. The light brown spots are shallow clay areas and the dark ones are deeper areas with sand. You can see divers bubbles almost in the middle of the photo. Photo is taken with a drone. Photo by Jaakko Haapamäki, Metsähallitus.

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