Dragon Eel (CR 11)

Large Dragon (Aquatic)
Alignment: Usually neutral evil
Initiative: +4; Senses: blindsense 30 ft., darkvision 60 ft., low-light vision, keen scent, Listen +18, and Spot +18
Languages: Aquan and Draconic, possibly Sahuagin and Common

AC: 27 (-1 size, +18 natural), touch 9, flat-footed 27
Hit Dice: 14d12+70 (161 hp)
Fort +14, Ref +9, Will +10
Speed: 20 ft., swim 60 ft.
Space: 10 ft./5 ft.
Base Attack +14; Grapple +26
Attack: Bite +21 melee
Full Attack: Bite +21 melee
Damage: Bite 4d8+12 or Powerful Charge 4d8+12 plus 2d6
Special Attacks/Actions: Improved grab, swallow whole
Abilities: Str 26, Dex 11, Con 21, Int 8, Wis 12, Cha 13
Special Qualities: DR 5/adamantine, immunity to magic sleep effects and paralysis
Feats: Cleave; Improved Bull Rush; Improved Initiative; Improved Sunder; Power Attack; Powerful Charge
Skills: Bluff +18, Hide +13, Listen +18, Sense Motive +18, Spot +18, and Swim +16
Advancement: 15-28 HD (large); 29-42 HD (Huge)
Climate/Terrain: Temperate aquatic
Organization: Solitary or pair
Treasure/Possessions: Standard

Source: Monster Manual III

A dragon eel prefers to attack ships by charging them, ramming holes in their sides beneath the waterline in an attempt to sink them. If an opponent is too large to swallow, a dragon eel attempts to grapple and then submerge with its foe, drowning it.

Improved Grab (Ex): To use this ability, a dragon eel must hit with its bite attack. It can then attempt to start a grapple as a free action without provoking attacks of opportunity. If it wins the grapple check, it establishes a hold and can attempt to swallow the foe the following round (see below).

Swallow Whole (Ex): A dragon eel can try to swallow a grabbed opponent of Medium or smaller size by making a successful grapple check. Once inside, the opponent takes 1d8+8 points of crushing damage plus 8 points of acid damage per round from the dragon eel's gizzard. A swallowed creature can cut its way out by using a light slashing or piercing weapon to deal 25 points of damage to the gizzard (AC 17). Once the creature exits, muscular action closes the hole; another swallowed opponent must cut its own way out. A large dragon eel's interior can hold 2 Medium, 8 Small, 32 Tiny, 128 Diminutive, or 512 Fine opponents.

Blindsense (Ex): A dragon eel can locate creatures underwater within 30 feet by non-visual means. Opponents the dragon eel can't actually see still have total concealment against the dragon eel. This ability works only when the dragon eel is underwater.

Keen Scent (Ex): A dragon eel can notice creatures by scent within 180 feet, and detect blood in the water up to a mile away.

Aquatic Subtype

Creatures with the aquatic subtype always have swim speeds and thus can move in water without making Swim checks. An aquatic creature can breathe underwater. It cannot also breathe air unless it has the amphibious special quality.