Poland's top leaders are taking part in the opening Saturday of a new – albeit unfinished – canal that they say will mean ships no longer must secure Russia's permission to sail from the Baltic Sea to the ports of the Vistula Lagoon.

The event was timed to mark 83 years since the Soviet invasion of Poland during World War II and to demonstrate symbolically the end of Moscow's say on the economy and development of a region that borders Russia's Kaliningrad exclave. The government says the waterway gives Poland full sovereignty in the northeastern region, which needs investment and economic development.

The canal, built at a cost of almost 2 billion zlotys ($420 million), cuts across the Vistula Spit, east of Gdansk, and was designed to allow ships to sail from the Baltic Sea and the Bay of Gdansk to Elblag and smaller ports of the lagoon without obtaining authorization to travel through Russia's Strait of Pilawa. It also shortens the Baltic-to-Elblag route by some 54 nautical miles.

Polish President Andrzej Duda, Prime Minister Mateusz Morawiecki and right-wing ruling party leader Jaroslaw Kaczynski plan to sail Saturday across the Vistula Spit to open the canal. Small ships and yachts are expected to be allowed in on Sunday.

However, cargo ships cannot use the passage until the approach to the Port of Elblag is deepened to 16 feet. The work is expected to cost 100 million zlotys ($21 million), which is a source of controversy between the national government and city authorities.