Australian's have a unique sense of humour. At the posted coordinates you shall find a sign that highlights this simple and sarcastic type of humour.
At the posted coordinates you shall find 6 yellow planks. To find the final location consider these PLANK 1 (OR P1), PLANK 2 (P2) ETC
On each plank, is a number of letters. On each plank, label the first letter 1 and so on until you get to the last letter.
NOTE: Some letters that are needed are missing - I have used an asterix here instead. The rest of the letters will help you to find the numbers required though.
THE CACHE CAN BE FOUND AT
S32 (check sum = 31)
(Plank 1; Letter 8)(P2;L2)(P6;L18)(P3;L1) / (P1;L2)(P3;10)(P6;L11)(P4;L6)(P1;4) / (P1;L2)(P3;10)(P6;L11) (P4;L6)(P1;4) / (P1;L8)(P5;L14)(*****)(P1;L6) / (P6;L2)(P2;L10)(P2;L11)
E151 (check sum = 32)
(Plank 1; Letter 4)(P4;L5)(P5;L2) / (P1;L14)(P2;L9)(*****) / (P4;L11)(P2;L9)(P3;L12)(P1;L6) / (P4;L10)(P6;L9)(*****) / (P6;L15)(P3;L5)(P1;L9).
In the cache, I have placed an extremely expensive weather measuring device. Feel free to measure the weather and take a photo.
Good Luck!