Looking seawards, the expanse of is impressive. The construction of a National Harbour of Refuge was first discussed in the early 19th century. For hundreds of years the shingle which blocked successive harbours was a problem. It was not really solved until the Admiralty Pier, begun in 1847 and completed in 1871, was built into deep water. In 1897 work commenced on the Eastern Arm, the Southern Breakwater and the extension to the Admiralty Pier, which was finished in 1909. This huge outer harbour was intended solely for Royal Navy use. The Dover Patrol was based here during World War I, but it was never used for the whole fleet. The Admiralty handed over the harbour to the Harbour Board in 1922 for commercial use and since the Second World War the port has developed enormously. In 2015 13 million passengers, 2.3 million tourist vehicles, 96,000 coaches, 2.5 million freight lorries and 120 cruise ships used the port.