Did we determine the following was too similar to the dire hippo in Sandstorm? Or is it worth a quick conversion?
CLIMATE/TERRAIN: Tropical lakes and rivers
ORGANIZATION: Family group
NO. APPEARING: 1-4
ARMOR CLASS: 4
MOVEMENT: 6; SW 12
HIT DICE: 10 +5
NO. OF ATTACKS: 1
DAMAGE/ATTACKS: 5-20 or 4-16
SPECIAL ATTACKS: Surprise
SIZE: L (12. long)
MORALE: Unsteady (7)
XP VALUE: 2,000 (males), 1,400 (females)
This massive animal is the direct ancestor of the behemoth (AD&D 1st Edition Monster Manual II) but has two differences, detailed below.
Combat: First, the giant hippo has smaller tusks than the behemoth, doing only 5-20 hp damage (4-16 for females). Second, the giant hippo has eyes that stick up above the skull like periscopes. Thus, it can hide its entire body below the water, with only its eyes above the surface. This gives it a -2 modifier to surprise rolls against swimmers and boats.
Habitat/Society: When a group is encountered, it will typically be one male (bull) and 1-3 females (cows). Only the young are subject to attack, and only by the largest predators.
I'd give them the Hippopotamus's feats plus Alertness.
Sadly, they don't have the BAB for Improved Critical (bite).
The size limit and DC for their Overturn SQ seems very low. I'd have thought they'd be able to overturn boats at least their own size & weight. At +1 DC per 100 lb and Str 34 they couldn't flip a boat weighing more than 1200 lbs, but its maximum carrying load is 16,800 pounds.
Overturn (Ex): Behemoths can overturn small watercraft on a Strength check, the DC depends on the total weight of the craft and contents: DC20 if the weight it a light load for the behemoth (up to 5,600 pounds for a typical behemoth); DC 25 for a medium load (up to 11,200 pounds); and DC 30 for a heavy load (up to 16,800 pounds). If the check succeeds, the boat overturns, spilling its passengers and contents into the water.