Spears of the merling king
The spears of the merling king are a geological feature of Blackwater Bay named after the Merling King, a deity revered by sailors. Barren sea monts rise from the floor of the bay and form spear-like rock formations that can rise above the surface of the water for up to a hundred feet. For every spear that breaks the surface a dozen more lie just beneath.
It is considered treacherous for any ship to sail into the spears, as the hidden monts will rip the bottom of any passing vessel.