Coal occurs in many places throughout the Bay but nowhere were the seams as promising as at Puponga, where the mine opened up in 1899. A railway linked the mine with Port Puponga where a long wharf, said by some to be the longest in the southern hemisphere, stood out into the shallow bay. The early 1900's saw the population of Puponga swell to several hundred, supporting two general stores, a billiard saloon, a bake-house, two boarding houses plus dance hall, post office and a two-teacher school.

The "Number-one" mine was closed by flooding and a strike in 1916; smaller seams were then worked. The township shrank. The nearby "Cape Mine" closed in the early 1930’s and the "Township Mine" closed ten years later. However, a resurgence of interest saw the old "Number-one Mine" dewatered by electric pumps in the late 1950’s and this produced coal until the early 1970’s when all mining stopped.