Why did Western European nations send explorers in seach of a Northwest passage?

If navigable, the discovery of a Northwest Passage would have provided a more direct and efficient trade route to China than Europeans possessed at the time. Before the Suez and Panama canals were created, trade between the Atlantic and Pacific Oceans was only facilitated by long journeys past the southernmost reaches of Africa and South America, resulting in voyages that were many months long. The Northwest passage would have made these trips much more efficient and provided instant boosts to traders' profitability.