A Whirlpool is a dangerous natural phenomenon of the open sea. These gigantic, swirling vortexes can suck in even the biggest ships and eat them whole. Thankfully, they are also so big that it is easy to avoid them, as they move very slowly. Sometimes, steering the ship into a whirlpool can have strange effects.
In Ultima III there was only one whirlpool. However, it travelled quickly and always threatened to swallow the ship. Directing the ship into it led to the loss of the ship, but would transport its passengers to the lost island of Ambrosia. By Ultima IV, several whirlpools could be found at sea. Getting into one with the ship would result in the ship reappearing in Lock Lake. Some years later, Captain Johne's ship, the Ararat, was swallowed by a whirlpool, sending it into the Underworld beneath Despise. The Avatar had the option of doing the same in Ultima V.
After this time, the whirlpools vanished. Despite being mentioned as endangering the ship traffic in Ultima IX, only a small one is seen, in a cut scene.
A huge swirling --WhirlPool-- engulfs you and your ship dragging both to a watery grave!...
As the water enters your lungs you pass into Darkness!
You awaken on the shores of a forgotten Land
Your ship and crew lost to the sea!
- entering the whirlpool in Ultima III
Farther out to sea roam many mythical creatures. The unwary voyager will likely encounter Giant Squids, Nixies, poisonous Serpents, and mystical Seahorses. The ever-present danger of whirlpools and waterspouts make seafaring a hazardous experience at best.