"I get it. It looks insanely cool when the ships rise from the depths. Such inspires the imagination and causes fancy to take flight. But let's not dismiss logic with our need for the wondrous." - from the memoirs of Lewin Von Treet, Vault: the Land of Stuff and Things
When the dwarves of Dagmar wished to continue their expansion west to find new treasures hidden beneath the earth, many of them simply walked the elven domain of Lyr'Lowain, content to bear the barbs of ridicule and pay the tolls, both monetary and emotional. However, some few Thanes of the dwarves wished to circumvent the forest by traveling south on their journey. Some many Thanes found themselves in the mountains north of what is now Jawhara, but one, Thane Dor Cleftmag, decided that the Kindred Sea was where he would make his journey west, despite having very little in the way of watercraft.
However, Thane Dor was a resourceful man, and set about building his fleet to take his clan across the sea to the inevitable mountain ranges of the far west. Having little wooded area on hand from which to source this fleet, Thane Dor turned instead to sporestone, a rock so light and porous, it floated when thrown into water.
For several years Dor's clan mined sporestone and built the best approximations of ships they could imagine, having never done so before. The result was both ridiculous and magnificent. Dwarven minds untethered to traditional ship-craft were encouraged to untamed imagination. Gargantuan vessels which could only be named "ship" in the most liberal use of the term, were built upon the coast. Thousands of ships, each visually distinct from the last, lined the sands south of Lyr'Lowain. Such was their oddity and intrigue that the elves of the forests came by the droves to see Dor's fleet. Other dwarven clans watched carefully as their cousins crafted such magnificent instruments of travel, the likes of which no dwarf had ever attempted.
At last came the fateful day, and the thousands of ships of Dor's fleet were set to water, and against all odds, and to the surprise of the elves, and to the admiration of the dwarves, and to the wonders of history, Dor's fleet made of stone floated and clipped through the water's surface, carrying Dor's clan west.
It was mere days later, after the coast was left far behind, that the first ship began taking on water. Apparently, the sporestone's porous nature which allowed its buoyancy, also very slowly took on water until completely saturated. The first ship sank five days into the journey. More followed. Every day, dozens of Dor's fleet sank to the depths, and the dwarves aboard were lost to the Kindred Sea.
After a week of travel, only a handful of the larger ships remained, and they made landfall on the first coast they could find; a place that is now known as Dorhomme. Dor's fleets was lost to the depths, but that was not the end of the story for his stonespore ships.
Weeks later, having been completely saturated with water, something very odd happened to the stonespore. Through some organic property which likely helped form many of the underground rivers and seas of Dagmar, the stonespore rejected all of the water, pushing it out, a trait the dwarves of at least that time had never experienced before. As a result, Dor's fleet, one by one, shot up from the depths, emerging from the Kindred Sea like massive projectiles shot from a cannon. Each ship erupted from the surface, shot into the air, and landed back on the surface, and began to once again take on water.
That part of the sea is now known as the Bay of Dor's Dunk, and the ships continue to engage in their eternal dance of sinking and firing back up to the surface. They've taken on a mystical quality, with many denizens of Vault believing the ships are haunted, and emerge to claim the lives of sailors who have broken trust with the ocean. Indeed, there have been many occurrences of ships traversing the Bay of Dor's Dunk being destroyed through a collision of an emerging ship from the depths. And since Dor's fleet is made of stone, however porous, they always emerge the better for such an encounter. That same quality, however, makes them useless as vessels, and so no privateer or sailor would care to claim them.
And so Dor's fleet continues its rise and fall to this day.