Mystic owes its very existence to the Atlantic Ocean. Settlement of what would become Mystic dates back to the 17th century, and even then shipbuilding and fishing were the primary occupations of the community's inhabitants. A true understanding of Mystic, and the rest of New England, for that matter, must begin with the vast body of water that exerted so much influence on its early development.
Earth has been called the Blue Planet for good reason. Two-thirds of this ball of rock spinning through space is covered by water, after all, and the Atlantic by itself, at approximately thirty-two million square miles accounts for roughly one-fifth of the Earth's surface, even when its various subsidiary seas, bays, gulfs, inlets and sounds are excluded. In terms of volume, the Atlantic contains around seventy-seven million cubic miles of water. That is a lot of H2O.
The Atlantic's average depth is just under two and a half miles, but north of the Puerto Rico lies a decline of more than twice that depth. The Puerto Rico Trench is about five hundred miles long and sixty miles wide (or as Lex would have put things, two hundred seventeen wings by twenty-six). By way of comparison, Arizona's Grand Canyon is a mere two hundred seventy-seven miles long, eighteen miles wide and only a little over a mile deep. The reason that the Grand Canyon gets so much tourist trade and the Puerto Rico Trench so little is essentially the same as applies to any real-estate: location, location, location. In the Trench, light is but a rumor and the pressure would crush the strongest man-made objects like so much bubble wrap.
Towards the Trench's western end, about one hundred miles northwest of San Juan, is the Milwaukee Depth, the very deepest point in the deepest canyon in this vast body of water. Very little is known about this place beyond its name and depth. No human eyes have ever seen its wonders.
Nevertheless, at the same time Gloria yelled "You slept with Zoot!", 1750 miles SSE of Mystic, five miles below the surface, at the very bottom of the Milwaukee Depth, something stirred. Something very old, very large and very, very tired turned over in its sea bed and wondered if what it had sensed was a dream. Twice now it had felt similar disruptions in the fabric of its world, twice after years beyond its capacity to count.
The sole sentient inhabitant of the Milwaukee Depth resumed its long slumber, but fitfully. One occurrence could be ignored. Two in short order could be discounted. A third, however, would be sufficient reason to return to wakefulness. And then the surface world would once again know the full force of its presence.