Getting Under the Ice and Into the Water !

Use a big drill !

A work crew drives out in tracked vehicles to a prospective dive site near McMurdo Station. The crew uses a large auger mounted on the back of a tracked vehicle to bore holes through the ice


These holes will be used by scuba divers from McMurdo Station to get under the ice.

Two holes are drilled; a secondary safety hole is drilled a short distance away from the primary dive hole. Seawater comes up the auger when it has drilled all the way through the six foot thick sea ice ceiling.


The work crew sleds a dive hut out to the dive site and parks it directly over the primary dive hole they just drilled. As shown here, snow is piled around the hut's base to seal out the strong Antarctic wind; otherwise snow will blow into the hut through the hole in the hut's floor. Warmed inside by a heater, the scuba diver is protected from the elements while suiting up and getting in and out of the water.


Here's the primary dive hole under the dive hut. The water is near the top of a dive hole and the diver drops down six feet through that hole of ice until coming out under the sea ice ceiling. Obviously the diver cannot be claustrophobic ! There is a layer of platelet ice beneath the sea ice consisting of small ice crystals and large platelets; these are dislodged by divers' bubbles and float into the hole as seen here. A long-handled dipnet is used to keep the dive hole open and free of this ice.


A weighted drop line (seen here at the left of the diver) hangs straight down from the primary dive hole and has the following attached: black and white checkered flags, two to three strobes, and a pony bottle (extra emergency air) with regulator. The drop line can be used to descend to and ascend from the bottom immediately under the dive hole if there is a strong underwater current. The drop line is also a useful point of reference for the diver's safety stops to prevent decompression illness. The diver sees the flags close by and can see those strobes from far, far away. As the submerged diver looks up, the primary dive hole is rather dark since there is a hut over it (though still lighter in shade than the sea ice ceiling).

The secondary dive hole is a safety hole out in the open a short distance away from the dive hut. It is used in case the primary hole is blocked by a Weddell seal. Topside, the safety hole is marked with a flag pole (so the divers can find it after a blizzard) and is covered with a foam plug when not in use (to prevent freeze-over).

When a submerged diver looks up at the sea ice ceiling, the secondary hole has bright light streaming down on a sunny day, because it is out in the open and not under the dive hut. This bright light shining down the hole makes it easy for the diver to spot the dive hut and hole location from far away. It is easy to dive safely under the ice by remaining in the vicinity of these dive holes. There was usually only a very slow current so a diver didn't have to worry about getting swept away from the dive hole. There was no underwater surge complicating diver activities. Due to the ice ceiling, there were no waves affecting dive operations at the surface. In addition, we didn't have to pay attention to tides. Antarctic tidal movement is unique in the world's oceans because there are no significant land masses to impede the East/West (counterclockwise) sweep of the tides around the Antarctic continent [1]. Antarctic tidal movement is principally a progressive wave, and the tide is diurnal (one high water and one low water each tidal day, a lunar day of 24 hours and 50 minutes) [1].



If it is very cold, particularly in a strong wind as shown here, an ice crust slowly forms over the outside secondary dive hole. This crust has to be removed so that submerged divers can exit through this outside hole in an emergency. The ice crust is broken up with a pole or chipper bar (in the diver's hands) and then pieces are fished out with a dipnet (behind the diver).


Diving under the ice from a dive hut is comparative luxury compared to diving out in the open. At locations far away from McMurdo Station, a hut may be unavailable (like Discovery Bluff at Granite Harbor as shown here). Divers then enter the water through holes in sea ice cracks, either seal-made or man-made. This hole was seal-made and was shared with Weddell seals. Weddell seals enlarge holes in sea ice cracks for their use and keep them open throughout the year.If seal-made holes are unavailable, divers may open up a hole along a crack, using hand tools or chainsaws.


When diving close to McMurdo Station, a hole can be drilled in the ice (as shown above), or a Weddell seal hole can be used (as shown here at Turtle Rock). There may be a bit of wiggling involved to fit through restrictions in a Weddell seal hole. Here a diver has finished a dive and has handed out his air tank. Next he will lift out his weight harness, and then hoist himself out of the hole.

Here's a diver's eye view looking up at a Weddell sea hole used by our team to dive. The Weddell seals keep these holes open year round with their teeth, pivoting around in the hole, gnawing at the ice. That's why this seal hole looks so round. If divers are polite and ask first, the Weddell seals will let divers use these holes. Divers don't linger in these seal holes for very long, because the seals need them to breathe while in the water, and to get in and out of the water. One member of our dive team was poked about his rear end as he floated in a seal hole. Another member of our dive team waited underwater to exit, while two Weddell seals fought it out over temporary turf rights to the hole.


Here's another diver's eye view looking up at a Weddell sea hole used to dive on a grounded iceberg offshore Cape Barne (no dive hut). You are looking up at the underside of a crumpled pressure ridge of sea ice alongside that grounded iceberg. You can see the drop line hanging down from the hole and used by the divers for a point of reference and tie-off for emergency air supply. When there is a current, the drop line is used for handholds while descending to the seafloor and ascending to the surface, in order to avoid drifting away with the current.

1: Sailing Directions (Planning Guide & Enroute) Antarctica. Publication 200. National Imagery and Mapping Agency, Bethesda, Maryland. 1997. page 77

Text ©Peter Brueggeman. Photographs ©Peter Brueggeman, Kevin Hoefling, & Norbert Wu. Photographs may not be used in any form without the express written permission of Peter Brueggeman, Kevin Hoefling, & Norbert Wu.. Norbert Wu no longer grants permission for uncompensated use of his photos under any circumstances whatsoever; want more info?