The Moskstraumen is the tidal current that runs between the southern tip of Moskenesøya and the small islands of Mosken and Vaeroy — one of the strongest tidal currents anywhere in the world, reaching speeds of up to five knots when wind and tide oppose each other. Medieval sailors described it as a permanent whirlpool capable of swallowing ships whole. That was exaggeration, but not by as much as you might expect: in rough conditions the Moskstraumen creates standing waves, violent eddies, and a surface chop that is deeply disorienting. Vessels do still get into trouble here.
Every visitor to Værøy crosses it on the ferry from Moskenes. On a calm summer day it looks unremarkable — some turbulence, an occasional confused wave, the water a slightly different color where the currents meet. On a rough autumn day the same crossing is an experience you won't easily forget. The ferry handles it without drama, but the physics happening underneath are obvious, and there's something clarifying about crossing a stretch of water that scared Viking sailors.
Edgar Allan Poe read published accounts of the Moskstraumen and made it the setting of "A Descent into the Maelström" in 1841; Jules Verne sent the Nautilus through it in Twenty Thousand Leagues Under the Sea. Both stories drew on the real geography. The current is strongest during spring tides, particularly when a strong wind blows against the tidal flow — if you can arrange your crossing to coincide with this, do it.