Triton (CR 2)

Medium Outsider (Native and Water)
Alignment: Always neutral good
Initiative: +0; Senses: darkvision 60 ft., Listen +7, and Spot +7

AC: 16 (+6 natural), touch 10, flat-footed 16
Hit Dice: 3d8+3 (16 hp)
Fort +4, Ref +3, Will +4
Speed: 5 ft., swim 40 ft.
Space: 5 ft./5 ft.
Base Attack +3; Grapple +4
Attack: Trident +4 melee or heavy crossbow +3 ranged
Full Attack: Trident +4 melee or heavy crossbow +3 ranged
Damage: Trident 1d8+1; or heavy crossbow 1d10/19-20
Special Attacks/Actions: Spell-like abilities
Abilities: Str 12, Dex 10, Con 12, Int 13, Wis 13, Cha 11
Special Qualities:
Feats: Mounted Combat; Ride-By Attack
Skills: Craft (any one) +7, Diplomacy +6, Hide +6, Listen +7, Move Silently +6, Ride +6, Search +7, Sense Motive +7, Spot +7, Survival +7 (+9 following tracks), and Swim +9
Advancement: 4-9 HD (Medium-size)
Climate/Terrain: Temperate aquatic
Organization: Company (2-5), squad (6-11), or band (20-80)
Treasure/Possessions: Standard

Source: Monster Manual

Spell-Like Abilities: A triton can use summon nature's ally III once per day as the spell cast by a 5th-level sorcerer, often choosing water elementals for their companions.

Native Subtype

A subtype applied only to outsiders. These creatures have mortal ancestors or a strong connection to the Material Plane and can be raised, reincarnated, or resurrected just as other living creatures can be. Creatures with this subtype are native to the Material Plane (hence the subtype's name).

Unlike true outsiders, native outsiders need to eat and sleep.

Water Subtype

This subtype usually is used for elementals and outsiders with a connection to the Elemental Plane of Water. Creatures with the water subtype always have swim speeds and can move in water without making Swim checks. A water creature can breathe underwater and usually can breathe air as well.