The Great Slack

The rare spring tidal event when flood and ebb stack twice over and the Narrows channel drops to bare rock for a single cold hour, opening the Wrack-Maw and every deep sink that is normally never fully exposed.

The great slacks come weeks apart, tied to spring tides compounding with the mere's own seasonal drain — the Tide-Stones record their timing in pre-Imperial incision and the Hessk read those marks the way others read almanacs. In the hour the Great Slack holds, the Wrack-Maw opens, the Drowned Bell shows its whole mouth above the chop, and everything the ordinary ebb leaves under water stands briefly in air. An hour is the window; misjudge the return by minutes and the make catches you inside the deep sinks. The Tide-Pickers time their most ambitious runs to the great slacks, and they still mostly don't run the Wrack-Maw.