Revised from some suggestions I received: Moved attacks around to be more realistic, added racial skills based on a porpoise (since there isn't a seal in the Monster Manual). Upped the strength slightly in keeping with MM guidelines. Kept Improved init, as dire seals are highly agile and quick reflexed, and prefer to snap out at large schools of fish and penguins rather than tracking them over a long distance underwater.
Climate: Any aquatic or cold plains; CR: 3; Stats: 18+4,18+4,23+6,2-5,6-2,12+1; HD: 3d8+18 (32 HP); AC: 16 (13 Touch, 12 Flatfoot); Init: +8; Saves: 9,7,-1; Morale: +12 (Brave); Face: 5/10/10; Base Attack/Grapple: +2/+10; Attacks: bite (1d8+4) +5 Melee; Full Attack: bite (1d8+4) +5 Melee and 2 flippers (1d6+2) +3 Melee; Speed: 30 (6), Swim 80 (16); Special Qualities: Scent; Special Attacks: Trample;
Skills: Hide +8*, Survival +6*, Swim +14; Feats: Improved Initiative, Multiattack; Armor: Dex (4), Natural (3), Size (-1); Alignment: Always neutral; Organization: Solitary or pack (2-20); Languages Known: None; Treasure: None;
With a huge splash of water and a tremendous sound like a small fog horn blasting, a fifteen foot tall, ten foot long seal jumps up onto the ground. Its thick, pure white skin glistens in the cold sun, and its eyes seem to have a strange light of curiosity to them, if not intelligence.
Dire seals are a rare offshoot of the normal seal line. Like their smaller cousins, they are found mostly in arctic environments, and can survive cold temperatures and harsh winters that would kill most other creatures. They can swim with the greatest of ease, and hold their breath for up to 8 hours at a time without surfacing. They are usually highly inquisitive about new things (i.e. adventurers) and are rarely hostile unless provoked or come upon while they have a child with them.
Hold Breath: A dire seal can hold its breath for a number of rounds equal to 50 x its constitution score before it risks drowning.
Skills: A dire seal has a +8 racial bonus on any swim check to perform some special action or avoid a hazard. It can always choose to take 10 on a swim check, even if distracted or endangered. It can use the run action while swimming, provided it swims in a straight line.
*A dire seal has a +4 racial bonus on hide check performed in snowy environments or underwater.
*A dire seal has a +4 racial bonus on survival checks performed to resist the effects of severe freezing environments.