According to the introduction:

This medallic collection illustrates many of the foremost maritime achievements of Great Britain. Chronologically, a start is made with a representation of the Tudor ship-of-war, the Great Harry. She was built by Henry VIII, who in 1546 established a naval administration which, under varying names, has had a continuing existence ever since.

The collection covers adventurous trafficking by merchant venturers throughout the world's oceans and seas; also exploration, expansion war. It commemorates many of the most important measures which help to safeguard life at sea, invention and many other activities pertaining to the business of a great maritime nation. It ends with such recent events as the launching of the Queen Elizabeth II, possibly the last of the giant liners which were once so splendid a feature of the Atlantic trade; the advent of the nuclear-powered submarine Dreadnought, and the single-handed circumnavigation of the globe by Sir Francis Chichester in his yacht Gypsy Moth IV. Although every side of the nautical theme is represented, there is considerable emphasis on later times, and thus on events in which living people have been actively concerned.

Among our many subjects are the earliest efforts to discover a north west passage from the Atlantic to the Pacific, and thus to the riches of the Orient; the defeat of the Armada in 1588; the capture of Gibraltar in the 18th century; the victories of Nelson and other famous admirals. The collection covers the exploration and voyaging of Drake, Cook, Vancouver, and Fitzroy of the Beagle; progress in every direction of shipwrightry from Tudor times, through the daring experiments of Brunel in the Victorian era, to the latest advances and newest materials. The work of Trinity House, the Corporation of Lloyds and the Royal National Lifeboat Institution has its rightful place, as has such an event as the foundation of the East India Company, which exerted such inuence upon the expansion of British interests overseas.

Great Britain remains a leading maritime nation, whose work and example have enriched others besides herself. This medallic history enshrines in permanent form the great events of what is a fine and continuing story.