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GOLF 4-3-9 Antarctica Expedition 2012



Turtle Rock
0 m above sea level


After polishing up on my diving experience at dive holes close to town, we moved north to explore two new dive sites, one at Cape Evans and one at Turtle Rock, just south of the Erebus Glacier Tongue.   Both dive holes were established for ecological studies, including the macro-fauna as well as microbial communities.  Both of them are set on seafloor that is made up of volcanic rocks and of interest to our study. Henry Kaiser was with us on both occasions and shot more video for us. Material from this dive is cut into a YouTube video that can be watched at the B-480 YouTube channel: 

We started out at the Cape Evans site near Hut Beach. There were amazing numbers of small sea-urchins and pretty little (purple) sea stars, but the most unique aspect of this dive was the underside of the sea-ice that looked very much like a surrealistic painting.  The canvas is made up of a seemingly endless, smooth ice layer, covered with a translucent layer of brownish-greenish algae. It is dotted with white spots resembling recessed lighting and “black spots” that are effectively black mirrors made by the divers’ air bubbles reflecting the dark seafloor.  Our “recessed lighting” offers white light to come through a hole in the algae cover, caused by the brines that seep down into seawater from the growing sea Ice above.  Many of the light spots have “icicles” that protrude down from the sea ice, called brinicles.  Those brinicles form when the super-cold brine comes down from the sea-ice and actually freezes the sea-ice below. Anybody who has never heard about this, should check out a spectacular time-lapse movie that shows the growth of such brinicles, a cut taken from by BBC series Frozen Planet.  It is awesome.

The Turtle Rock dive site is very different from the smooth ice at Cape Evans.  The sea ice is all broken up and tangled along the shore line forming so-called compression ridges.  Such compression ridges are formed from the expansion of sea-ice and the tidal heaves hat break and tilt up entire slabs of sea-ice creating a deadly maze along the shore line.  Slabs stick out between four and ten feet, often separated by cracks that are deathtraps for unsuspecting humans, but a convenient breathing hole for the Weddell Seals.  Before going down below the ice it is good to remember that everything that sticks out above will also protrude deeper below!

The turtle island dive hole is seaward from these compression ridges, but landward of a (hopefully) sealed crack in the sea ice.  As we descended into the dive hole the light was pretty dim, except that seaward crack showing up as a white line from below.  It appeared to be healed nicely so there was no issue with the hut being in the wrong place.  We swam shoreward, of course, to explore the underwater caves that exist below the compression ridges, hopefully with a lot of seals frolicking below.  Well the seal story did not exactly pan out, we saw only one at a distance, all the others were sunning themselves at the surface above.  However, we were NOT disappointed by the scenery: In some places the sun was shining straight through holes in the ice, very much like a spotlights.  When you get close to the light spot on the ground you see the light flickering from the ripples in the water surface. As we approached the pressure ridges we actually have to dive down below the tilted ice slabs and then we entered an amazingly large light room.  The walls seem to be made of clouds made of colors that range from bright white near the top to a range of hues of light and dark blue.  The seafloors made of gravel that shaped with grooves like a Zen Garden, probably from ice slabs scraping over the ground.  Much of the ground is covered with anchor ice that is growing in large blades from the bottom up.  There were also some amazingly large brinicles and we saw a few seals, but fewer than we expected.  Again, check out Henry’s movie on the B 470 website!


Now I have to get ready for my final set of dives that include the recovery of our experiments and sampling some environmental samples for our microbial ecology project.