While on land, a Sea Demon will use half of its tentacles to
move and the other half to fight with. The striking tentacle of a
Sea Demon does 1-10 (1-8) hit points of damage. Each round
after the initial hit, the creature will have its prey captured within
the tentacle, and double damage will be taken, 2-20 (2-16), each
round thereafter unless the tentacle is severed or loosened.


The tentacles grip with a strength of 18/91 (18/76). If the
creature being crushed is as strong or stronger, it can negate
the crushing damage, but it will not be free of the tentacle. Two
rounds after the tentacle has hit, the Sea Demon will drag its
victim to its great beak, which does 5-30 (5-20) hit points of
damage.

While in the sea, there is a good chance that a Sea Demon will
attack ships passing close to its lair. Multiply the surface distance, in miles, from the ship to the lair by 20% to get the percentage that the creature will not attack the passing ship.
After detecting and deciding to attack a ship, the Sea Demon
takes 2 turns to get to a shallow depth, and 2-12 turns (depending on the distance) to catch up with the ship.


Any ship seized by a Sea Demon will come to a full stop in one 
turn. The creature will then attempt to sink the ship, attacking
whatever or whoever is aboard if the prey happens to get within
reach of a tentacle.

As long as six tentacles can grasp the ship, the Sea Demon
will damage the ship at the rate of 4 (3) structural points per
melee round. If 5 (4) or more tentacles are severed (each tentacle will take 20 (16) hit points of damage over and above the Sea
Demon’s regular hit points), the creature will retreat to 500 feet
below the ship, or to halfway between the bottom and the keel if
the sea is too shallow. It will then begin spinning, causing a
giant whirlpool to form under the ship; this takes one turn. Once
a ship is caught in the whirlpool, it will be destroyed in five turns.
To escape the whirlpool, a saving throw must be made with
percentile dice. The number of the ship’s remaining structural
points is multiplied by two and becomes the number needed to
save. For example, if a galley has 39 remaining points, to escape
the whirlpool a 78 or less must be thrown. This is assuming that
the galley has oars left to row with, and a crew to man them, and
that sailing ships still have sails and a wind to fill them.

If the ship escapes the whirlpool, the Sea Demon will not
attempt to pursue, because it needs to spend at least one day
recovering from the exertion of creating the whirlpool, but the
Sea Demon will be certain to sense the same ship if it comes
within 10 miles of its lair on a later day, and will attempt to
destroy it again. If the Sea Demon has lost more than half of its
tentacles, it will not be able to create the whirlpool. Sea Demons
will regenerate lost tentacles at the rate of 4 (3) feet per tentacle
per week. Sea Demons will not attack passing ships if their
wounded tentacles are less than half healed.