Entitled 20th Century Sea Power, it uses intricate models, paintings and audio-visual displays to set out a stirring, glorious tale of national decline.
Britain entered this century as the world's greatest maritime power with the largest naval and merchant fleets and the biggest ship building industry.
As the century closes only fragments of that industry survive and Britain's merchant fleet is the world's 16th largest.
The museum had to find a foreign sponsor to pay for the exhibition. The Taiwanese Evergreen Group, which is the world's largest cargo container line, came up with the necessary donation of pounds 400,000. A huge model of one of its vast modern container ships is on display.
Among all the video screens and oil paintings showing great ships and battles one small watercolour by John Worsley seems particularly poignant.
It shows British naval officers at a German prisoner of war camp in 1944: trapped far from the sea they are reduced to sailing model yachts on the camp pond.