Today, land-locked states which have merchant vessel fleets include Armenia, Austria, Azerbaijan, Bolivia, Ethiopia, Hungary, Kazakhstan, Laos, Luxembourg, Mongolia, Moldova, Paraguay, Slovakia, Switzerland and Turkmenistan, though of these, only Ethiopia and Mongolia have no river/sea port from which the high sea can be reached.
At the same time, the states with access to the Caspian Sea (Azerbaijan, Kazakhstan, Turkmenistan) can gain access by water to the Black, Baltic and White Seas through the Unified Deep Water System of European Russia (UDWS) on the basis of international agreements.
Prior to World War I, Switzerland had denied several requests from merchant ships to fly the Swiss flag.
After World War I, the creation of several new landlocked states, such as Czechoslovakia, Austria, and Hungary, caused the Great Powers to reconsider the issue.
The Declaration was created to reflect the new consensus and was concluded and signed on 20 April 1921 by 25 states in Barcelona, Spain, at the League of Nations Conference on Communications and Transit, as an addendum to the longer Barcelona Convention and Statute on the Regime of Navigable Waterways of International Concern, which was concluded on the same day.