Beneath, and well beyond, the boundaries of the Village of Cumberland and toward the fringes of Courtenay lie a significant array of underground workings and boreholes from the operations of the Canadian Collieries (Dunsmuir) Ltd. This mine was part of the first phase of coal mining developed on Vancouver Island. From 1888 to 1953, 14.5 million tonnes of coal were extracted from the Comox basin. An additional 1.54 million tonnes were mined in the Tsable River area, about 11 kilometres southeast of Cumberland.

Before Dunsmuir ran the Comox operations, the Union Colliery Company ran the Comox Mines. Coal from Comox, and the neighbouring Nanaimo mines, was well known as a high-grade boiler and domestic heating fuel. The coal was transported to a shipping and bunkering terminal at Union Bay, on the shore of Baynes Sound.

Eight mines operated at Comox, named as No. 1 Mine through to No. 8 Mine. The workings consisted of boreholes, air shafts, mine entries, and an underground network of tunnels. A rail network was also developed to link the ore piles with the town and Union Bay. The old rail bed remains in place today as public trails. A series of survey monuments also remains on the surface today. These have been tracked down, beginning with a concrete monument located slightly below ground in the vicinity of Cumberland Park, and recorded to match the maps of the underground workings with the surface-level features today.

The mines at Comox were technically advanced for their time, with partial mechanization and electrification well before 1900. The first documented use of electricity underground was in the No. 4 Mine in 1891, when four electrically-driven coal-cutters were installed.