The thread of the sea legend is present at every location and moment of Gdynia's history. It is the whole story of the Polish commercial fleet. Starting from small tramp steamers called "Frenchmen", bought in 1926 in France by Polish Shipping, until the great expansion of the Polish Shipping Lines on the routes all over the globe in 1970s. A part of the legend are the great achievements of Polish oceanologists and sea biologists conducting their research from the northern polar waters of Antarctica coordinated by the Gdynia’s research centres, the Maritime Fishing Institute, the Maritime Department of Metrology and Water Management Institute, and scientists from the Gdynia’s ocean study centre of the Gdansk University. Finally, Gdynia was the great centre of the shipbuilding industry for decades. It was the birthplace of the largest and most advanced ships constructed in Poland, such as liquid gas carriers. After the transformation slump, the Gdynia's shipbuilding industry centre has revived gradually.
Moreover, Gdynia saw the start of the pioneer voyages under the white-and-red flag, as "Dar Pomorza" was the first Polish ship to sail round the world, to Cape Horn, and the post-war voyages round the world of Gdynia's sailing ships, "Dar Młodzieży", "Iskra" and "Zawisza Czarny".
Another chapter of the sea legend of Gdynia, although it is in fact over today, is the history of Polish fishery. From the boats of the Kashubian fishermen in the village of Gdynia, through the pre-war attempts to go outside the Baltic Sea to the dynamic growth in the post-war era. There were times when dozens of Polish trawlers caught fish in the deep-sea fisheries of the Northern Atlantic, the Pacific Ocean, at the coast of the Southern America and Africa. Closing fishing grounds by coastal states has made the Polish deep-sea fishery a historic and stormy part of the sea legend.

The sea legend of Gdynia is in fact identical to the sea history of the 2nd Republic. After the 2nd World War, the pioneers from Gdynia took over the extended sea industry. The Gdynia's sea legend is present everywhere.