Text on Flickr:
Far-sighted planners were talking of bridging HK harbour at the turn of the century. The urgency of linking HK island to the neighbouring Kowloon Peninsula has been made more immediate by traffic growth over the past decade. The growth rate for 1970 was 15%. Started in 1969, a cross-harbour tunnel is targeted for completion in the summer of 1972. Most of its length - totalling 6,062 feet - is being laid by sinking twin-tube sections into a shallow trench on the harbour bed, and then covering them with a blanket of rock and earth fill. Pictured: A twin-tube section nearing completion in the fabricating yard at Hingham, on the Kowloon Peninsula. (Source: HK Gov information Services).
Source: This image came from Flickr, see https://flickr.com/photo.gne?id=15913297848