These are the type of sea monsters Odysseus faced in Homer's "Odyssey" - giant creatures that swallowed huge amounts of water before belching them back out again. Well, sort of the like that.  

Situated outside of Bodø, Saltstraumen is a small strait that contains the world's strongest tidal current. Travelers crossing the maelstrom must be very careful because the waters form dangerous tidal whirlpools that have considerable downdraft. Even when the surface appears calm, there can still be underwater currents to look out for. 

There are, however, "time windows" when the current turns that allow easier passage for large ships. Every six hours, more than 105,000 gallons of water up to 20 knots (almost 25 miles per hour) rush through the sound connecting Saltenfjord and the Skjerstadfjord.

Expert guides who have plenty of experience crossing the straight will lead you through safe passage on your Norwegian cruise.

Why it happens

Saltstraumen, which means salt current, is created when the tide fills or empties the Skjerstad fjord. The height difference of the sea surface can be as much as 3 feet between the inside and the outside of the narrow sound. In an attempt to level out the two sides the sound, the water increases in speed and turns into a swirling whirlpool as big as 35 feet in diameter.

Fishing

Although voyagers on Scandinavian cruises never want to swim here, the surrounding waters are filled with fish, from cod to coalfish to halibut. Thus, it's no surprise that Saltstraumen is famous for its fishing opportunities. The world record for coalfish caught with a fishing pole was set here, in which the fish weighed in at 48 pounds. 

Some people rent tackle for fishing from shore and others fish from a boat. If you have extra time here, you can embark on a deep-sea fishing charters.

Hiking

With gorgeous mountain wilderness surrounding the strait, hiking and rambling abounds. You can even explore areas packed with archaelogical findings. 

Diving

For the real adrenaline buffs, diving makes for an amazing adventure. You can see a myriad of underwater fish, plants and sea creatures - though none quite as scary as what the fictional Odysseus met. National Geographic ranked Saltstraumen among its "Top 10 Diving Destinations."

Archeological discovery

More than 10,000 year ago, there was a human settlement in the Saltstraumen area. They lived on the edge of ice, sustained by the wealth of fish in fast-moving currents. The remains, which were discovered within the last 10 years, are among the oldest archeological findings in Norway.