Oct 242011


About the site

Lonsdale and Nepean Walls form two sides of the shipping channel through the Heads of Port Phillip Bay. With such a narrow opening to the large area of the Bay, the channel is also known as the Rip for the speed and volume of water that flows through it when the tide is running. A couple of times a day, the tide levels inside and outside the Bay are balanced, and the current stops for around 45 minutes…perfect for a dive.

Slack water timings are based on mathematical calculations by the Bureau of Meteorology and nature doesn’t always co-operate. Inevitably, if you’re running late at the boat ramp, slack water will be running early. It’s also important to consider the shipping schedule if you plan to dive an area of either wall that falls within the shipping channel. Success is all about timing. This particular shot was taken on a popular area of Lonsdale Wall that sits in the “emergency” shipping channel and can be dived without concerns about being run over by a tanker.

The quality of wall dives is strongly influenced by the direction the tide was running in before slack water. An ebbing tide will be carrying the dirt and debris from inside the Bay out to sea before it stops running, with a corresponding drop in visibility. A flood tide, on the other hand, flushes the entrance to the Bay with clear ocean water and can lead to stunning dives.Blue devil on Lonsdale Wall

With the high volumes of water passing through carrying lots of things to eat, the walls support a huge amount of stationary life. Covered in soft corals, sponges and other colourful and squishy things, there’s much more colour than on a tropical reef dive. Big overhangs are made yellow by a carpet of zooanthids, with cranky-faced Southern Blue Devils hanging out under ledges like this fine specimen in the second picture. This particular site sees the wall step down in 5m increments, dropping from 15m at the top to 60m+. Great vis lets you hang over the edge and feel the ocean drop away into the blue beneath you and fur seals drop by on occasion.

About the dive

This dive was one of my very first boat dives with the Canon 5D Mark II in 2009. After nervously electing to jump in with it in my hands, I descended into the blue water watching for bubbles coming out of the camera housing that might mean water was going in. The tide was still running very gently, and the first ten minutes of this dive were spent drifting along the wall. My first five minutes were spent fiddling with strobes and settings, and the odd test shot to see what photos would look like.

About the shot

I was just about prepared with settings when I realised the drifting current was about to swim me into this particular outcropping. The sponges were surrounded by reef fish, and I started back pedalling to try and set myself up for a shot. Of course, without enough experience with the wide angle lens, I backed up too far. Letting the current move me in slightly while playing with the f stop, I realised all the flailing and flashing had redistributed most of the fish to a more peaceful location – d’oh.

And so this shot is a compromise in this series, between the too-far-away, wrong-f-stop, too-dark, lots-of-fish shot at the start of the series and the close-enough, slightly-too-light, where-are-all-the-fish?? shot at the end. Can’t win ‘em all…and apparently, that spot on the wall has disappeared, because I can’t find it again to do a better job. Luckily, having shots like this helps me realise how far my underwater photography has come, and makes me optimistic about continuing to learn more and take better photos.

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