There is a sea which moves from ocean to ocean, sometimes taking only a few hours for ships to cross and at other times ships can become lost in it for months. Its location is rarely the same from year to year, and it almost never comes into shallow coastal waters. It looks much like other parts of the ocean and is quite difficult to discern, except in one important way.

On the Sea of Fancies, sailors begin to notice strange illusions and mirages, first far off and then closer as the vapours from the water take further effect. Ships have tried to anchor near illusory islands, with crew even jumping into the ocean, believing they were on dry sandy beaches. Captains have set their own sails on fire to dispel menaces only they could perceive. Men speak of spending days doing nothing but laughing, even to the point of exhausted collapse.

The effects of the Sea of Fancies are lessened by strong winds or storms, and many a ship has been saved from its own delusions only by a powerful gust of wind. However, self-inflicted injuries aren't the only risks in these strange waters - there is also a complete ecosystem which has evolved and which follows around the Sea wherever it ponderously moves.

Some of these creatures have learned to take advantage of the odd properties of their sea and will cloak themselves in illusions, even climbing on board ships while the crew resolutely ignore them, convinced they're witnessing yet another impossible apparition.

Fancy pirates, as they're known, ply the waters of the moving sea and swoop upon hapless vessels lost and adrift. Their own ships are of strange construction, with much higher masts than usual and with bunks and hammocks slung on high. This keeps the crew above the worst effects of the vapours, and when they must descend they wear face masks dipped in a mixture of pure, clean water and arcane concoctions which neutralise the breath of the waves.