Tapir
FREQUENCY: Common
NO. APPEARING: 1-6
ARMOR CLASS: 8
MOVE: 15"//6"
HIT DICE: 3
NO. OF ATTACKS: 1 bite
DAMAGE/ATTACK: 1-6
The tapir is normally one of the most peaceful of animals and is ill-equipped for combat; its hooves are soft and its teeth are dull. However, if cornered, a tapir will take a bite out of its attacker with its wide mouth, doing damage if it gets a solid bite.
The tapir swims well and can stay underwater for several minutes. It lives only in tropical forests along rivers.
Originally appeared in Dragon Magazine #137 (1988).
With the same size and Hit Dice, it looks like we can just customize a boar, replacing gore with bite, adding a swim speed, dropping ferocity (and possibly adding hold breath), and changing feats and skills.