pf2e.fyi
From Pathfinder #218: Titanbane, which isn't enabled.

The Ketos

COMPLEX HAZARD 7
Stealth +19 (expert)
Description A shadow the size of an island appears in the water beneath the ship.

Disable DC 27 Acrobatics, DC 27 Athletics, or DC 27 Diplomacy or DC 23 Sailing Lore to help the crew of the Tide Hunter escape the Ketos; three total successes are required to disable the hazard

AC 25; Fort +20, Ref +12
HP 60 (BT 30) Tentacle HP 60

Grasp of the Depths
Trigger The Tide Hunter enters the Ketos's hunting grounds

Effect The Ketos uses its eight tentacles to seize the ship, holding it in place. The hazard then rolls initiative.
Melee Tentacle +18, Damage 2d10+9 slashing

No multiple attack penalty

Routine (3 actions) The Ketos uses its actions to make tentacle Strikes against creatures aboard the Tide Hunter or within 30 feet of the ship.
Reset If three or more of its tentacles are destroyed, the Ketos releases the Tide Hunter and disappears into the ocean's depths to nurse its wounds. The monster does not return to this area for 24 hours.
Pathfinder #218: TitanbaneORC