The seas were predicted at 3m but long period.  Inside Botany Bay it was quite calm but as we got closer to Henry Head we could see the seas smashing against the rocks.  Minmi was a possibility as the sand line is well out from the shore. We anchored OK in about 15m at the anchor.  At the bottom it was surgy - no doubt due to the large and long swell.  The swell was also making the viz quite poor with a lot of sediment in the water.  We had to move the anchor out close to the sand line.  This took a bit of effort and chewed up our gas.  Finally at the sand line and there is a lack of fish as well.  We head West towards the trench proper but with such poor viz I am reluctant to go too far and call an about face.  We find the anchor again quite easily and explore the over hangs and cracks in this area which is quite east of our usual position.  A large cuttle resides under an over hang - I manage a pic of him (not a good one).  As they say, there are good dives and then there are experience dives.  This was one of the experience dives.