DAY 66: Day off in Mount Gambier
Mon 8th December 2007
Cloudy, cool, light drizzle occasionally
Lazy start and at the library by 0930 for free internet. After this I cycled the 1km to the Blue Lake visitor centre where the tours start from. The tour consisted of a guide taking us down to see the lagoon and explain how the water is used as the town (pop 23,000) drinking water supply.
The lake is a 25,000 year old volcanic crater which being below the water table subsequently filled up with water from the limestone aquifer.
It is approximately 600m by 1200m and some 70m deep. The colour is quite startlingly blue but in the summer only when water temperatures rise. Apparently the calcium carbonate crystals absorb red light and radiate blue at these temperatures, hence the colour. The level is falling over the years due to overuse and drier weather. Although it is said to be very pure, 0.5 mg/l chlorine is added as a precaution. 
The area around the Blue Lake is collectively known as the Crater Lakes area all related to volcanic activity. There is actually a mountain bike trail around the Blue Lake, and there are many walking trails also. The Centennial Tower stands at the highest 
point on the crater rim, and although there is a good path all the way up to it i was unable to climb on the bike - it must be at least 40% slope and i was afraid of the bike tipping over backwards! 
Another attraction worth a visit is the Lady Nelson visitor and Discovery Centre, which shares premises with the TIC. This houses some very up-to-date displays depicting the aboriginal origins of the area, the geological processes related to the volcanic activity, and a full-scale replica of the HMS Lady Nelson, a 60-tonne survey brig built in Deptford named after Horatio’s wife. She made her maiden voyage to Australia in 1800 and among many other feats of discovery was the first vessel to sail eastward through the Bass Strait. The inside of the ship is very small; it must have felt very cramped to the crew who lived in her for months and even years. 
Yet another ‘must see’ is the Umpherson Sinkhole, formed when water eroded a vertical fissure in the limestone to open, over thousands of years, an underground cavern, the roof of which later collapsed to leave a large hole some 130m diameter and 20m in depth. The base has been planted with flowers and is very pretty. As I descended the steps down into the hole I spotted a possum sat on a ledge. 
Apparently they get fed at night do come out in their dozens; the place is supposed to be very prettily lit at night also. 
In between all this I still managed a spag bol lunch, and yes Lyn I did order the f*****s too!
Full marks to the caravan park lady for taking the time to explain what there is to see here in MG, and also between here and Melbourne when she asked where I was going next.
