Shek Pik Reservoir is a reservoir in Shek Pik on Lantau Island in Hong Kong – it has a storage capacity of 24 million cubic metres and is the third largest reservoir in Hong Kong. Its history dates back to the mid-1950s where rapid population growth and economic development fuelled a need for additional sources of fresh water. The Government selected the Shek Pik Valley on Lantau Island as the most suitable location to build a new reservoir and works began in 1959. Located in a semi-basin, a huge dam and a network of outfall channels were constructed to funnel water from the surrounding mountains.

The design of the reservoir includes a large bellmouth spillway, which prevents water from overtopping and damaging the reservoir’s dam during floods. When the water reaches a certain height it will flow into this structure and drain into the sea.

A short trek away down a steep hill and along the coastal beach we reached the outflow portal from the spillway, where water would directly discharge into the sea.

The diameter of the tunnel is quite impressive, much larger than those of many railway tunnels and capable of handling huge quantities of water.

It was surprising to find other explorers in the tunnel, who were from a local hiking/adventure group.

Natural light filters down the vertical shaft of the spillway, which rises up over a hundred feet.

The huge retaining wall of the reservoir is topped by a large road, seen here from the drone’s view. The small white dots on the grass are grazing sheep who occupy the steep terrain adjacent to Shek Pik Prison.