Soon after this, the British Government began to mine coal at Koabong Bluff, at the north-east end of the island, in order to supply coal to warships on China station. Mining was by a combination of opencast, adit and shallow shaft workings, all about two miles from Coalpoint Wharf. About , the mines changed hands and the new operators sank two shafts about one mile inland. Coal was eventually produced in but production decreased until the mines were closed in Between and , outcrop workings were continued on a small scale by an enterprising marine engineer, but in a new company the New Central Borneo Co Ltd? In preference to shafts, it was decided to cut costs by driving a number of drifts. Two were within ft of the main railway line, from which branches were laid to serve them. By , it seems they were completed and in that year, the mines produced 18, tons of coal. Narrow gauge tubs were carried on a standard gauge transporter wagon. During construction a 2ft 5in gauge line was laid between the standard gauge to facilitate dirt removal.