I just ran into these while playing the save from the fill up the world topic
My adventuring group found itself in an uninteresting part of the world, an island that had mostly been explored. We decided to try and reach another continent. The only way to reach other known land is by crossing the crazy seas, which nobody seems to have ever done. We travelled to the coast and observed the sea for a full day and found that it was frozen for almost the entire day, only thawing around noon. Judging the distance on the map we decide that we should just be able to make it across the ocean in the time the sea is frozen.
As soon as the water freezes, we start running over the newly formed ice (fast travel is not possible on ice). We make good progress untill, after a few hours, night starts to fall. Suddenly, just at the edge of our vision, a huge slab of ice that we just travelled over shoots up, forming an impassible ice wall. With no way to go back we decide to move on. But the sound of breaking and shifting ice is all around us now. Our road ahead is often blocked by impassable walls and we have to travel around repeatedly. At this rate we are never going to make it across before the ice will thaw, if so, we are doomed, as nobody of us can swim.
Things get worse however, the shifting ice sometimes traps members of our adventuring group on different iceshelves. We have to leave them behind, there's no time to wait. The adventuring party shrinks from its original 7 members untill only myself and Alho sanctumcreeks are left. It's still dark, and fearing the night we decide to be carefull not to lose sight of eachother, as the bogeyman are unlikely to be far away.
Finally however I find myself on the other side of an ice wall, and I can't reach Alho, even though I know that he must be close. Even worse, I seem to be walled in on all sides, there's no way out, except for two deep fissures. Day is nearly breaking, and I quickly have to find a way out if I want to reach the coast before the ice melts. There's no other option but to try and go down through one of the fissures.
I jump into the nearly bottomless fissure, and am quite surprised to find that I don't fall to my death. My happines is shortlived, I'm deep under water, and being unable to swim, I can't reach the surface.
I guess the crazy seas are aptly named.