| Creature | Terrain | Climate | Campaign | Reference |
|---|---|---|---|---|
| Balaena | Water | Any | Planescape | PSII 14 |
| Barracuda | Water | Any | Any | MM 117 |
| Beaver | Water | Any | Any | MM 244 |
| Beaver, Giant | Water | Temp/Trop | Any | MAII 83 |
| Carp, Giant | Water | Any | Any | MM 117 |
| Catfish, Giant | Water | Any | Any | MM 117 |
| Crane, Giant | Water | Any | Any | OMII 26 |
| Dinosaur, Mosasaurus | Water | Any | Any | MAII 40 |
| Dinosaur, Nothosaurus | Water | Any | Any | MAII 41 |
| Dragon Turtle | Water | Temp/SubTrop | Any | MM 88 |
| Dragon, Linnorm, Sea | Water | Any | Any | MAI |
| Dragon, Oriental, Chiang Lung (River) | Water | Temp/Trop | Forgotten Realms | FR1MC |
| Dragon, Oriental, Shen Lung (Spirit) | Water | Temp/Trop | Forgotten Realms | FR1MC |
| Dragon, Oriental, Yu Lung (Carp) | Water | Temp/Trop | Forgotten Realms | FR1MC |
| Dragonfish | Water | Any | Any | MM 117 |
| Eel, Electric | Water | Any | Any | MM 117 |
| Eel, Giant | Water | Any | Any | MM 117 |
| Eel, Giant, Moray | Water | Any | Any | MAIII 37 |
| Eel, Marine | Water | Any | Any | MM 117 |
| Eel, Weed | Water | Any | Any | MM 117 |
| Elemental, Kin, Water, Nereid | Water | Temp/Trop | Any | MM 104 |
| Elemental, Kin, Water, Water Weird | Water | Any | Any | MM 104 |
| Elemental, Water | Water | Any | Any | MM 100 |
| Flawder | Water | Temp/Trop | Any | FFMC |
| Flawder, Chief | Water | Temp/Trop | Any | FFMC |
| Flawder, Leader | Water | Temp/Trop | Any | FFMC |
| Fossergrim | Water | Any | Any | LL 187 |
| Gar, Giant | Water | Any | Any | MM 117 |
| Genie, Marid | Water | Any | Any | MM 126 |
| Ghoul, Lacedon | Water | Any | Any | MM 131 |
| Golem, Shaboath | Water | Any | Any | MAIII 54 |
| Hag, Sea | Water | Any | Any | MM 181 |
| Hag, Spectral, Sea | Water | Any | Ravenloft | RVIII 53 |
| Hetfish | Water | Any | Any | MAII 52 |
| Hippocampus | Water | Any | Any | MM 189 |
| Hippopotamus | Water | Tropical | Any | MAII 84 |
| Hippopotamus, Minimal | Water | Tropical | Any | OMII 85 |
| Hobgoblin, Koalinth | Water | Temp/Trop | Any | MM 191 |
| Irridescent Plecoe | Water | Any | Any | MAII 55 |
| Ixitxachitl | Water | Tropical | Any | MM 209 |
| Ixitxachitl, Vampiric | Water | Tropical | Any | MM 209 |
| Ixitxachitl, Vampiric, Greater | Water | Tropical | Any | MM 209 |
| Kapoacinth | Water | Any | Any | MM 125 |
| Kappa | Water | Temp/Trop | Kara-Tur | KTMC |
| Kappa, Vampiric | Water | Temp/Trop | Kara-Tur | KTMC |
| Kappa-Ti | Water | Temp/Trop | Kara-Tur | KTMC |
| Kuo-Toa | Water | Any | Any | MM 215 |
| Kuo-Toa, Leaders | Water | Any | Any | MM 215 |
| Lake Monster, Undead | Water | Any | Any | MAI |
| Lamprey | Water | Any | Any | MM 117 |
| Lamprey, Giant | Water | Any | Any | MM 117 |
| Lemon Fish | Water | Any | Any | MAII 55 |
| Locathah | Water | Sub-Trop/Trop | Any | MM 228 |
| Masher | Water | Tropical | Any | MAII 52 |
| Morkoth | Water | Any | Any | MM 258 |
| Mudman | Water | Any | Any | MM 260 |
| Nixie | Water | Temperate | Any | MM 328 |
| Ogre, Aquatic | Water | Any | Any | MM 272 |
| Ogre, Aquatic, Chief | Water | Any | Any | MM 272 |
| Ogre, Aquatic, Female | Water | Any | Any | MM 272 |
| Ogre, Aquatic, Leader | Water | Any | Any | MM 272 |
| Ogre, Aquatic, Young | Water | Any | Any | MM 272 |
| Ooze, Crystal | Water | Any | Any | MM 278 |
| Otter | Water | Any | Any | MM 244 |
| Otter, Giant | Water | Any | Any | MAII 83 |
| Pike, Giant | Water | Any | Any | MM 117 |
| Ray, Manta | Water | Any | Any | MM 117 |
| Ray, Pungi | Water | Any | Any | MM 117 |
| Ray, Sting | Water | Any | Any | MM 117 |
| Reaver, Outcast | Water | Any | Ravenloft | RV 45 |
| Remnant, Aquatic | Water | Any | Ravenloft | RVIII 94 |
| Sea Horse, Giant | Water | Any | Any | MM 117 |
| Selkie | Water | Arctic/Sub-Arctic | Any | MM 311 |
| Selkie, Leader | Water | Sub-Arctic | Any | MM 311 |
| Shark | Water | Any | Any | MM 117 |
| Shark, Giant | Water | Any | Any | MM 117 |
| Sirine | Water | Temp/Trop | Any | MM 314 |
| Skuz | Water | Any | Forgotten Realms | FR2MC |
| Snake, Cobra, Water | Water | Any | Any | LL 169 |
| Snake, Sea, Giant | Water | Tropical | Any | MM 320 |
| Snake, Sea, Giant, Elder | Water | Tropical | Any | MM 321 |
| Spirit Folk, River | Water | Temp/Trop | Kara-Tur | KTMC |
| Sprite, Sea | Water | Tropical | Any | MM 328 |
| Squid, Giant | Water | Any | Any | MM 331 |
| Squid, Kraken | Water | Any | Any | MM 331 |
| Swan | Water | Temp/Trop | Any | MM 27 |
| Tanar'ri, Greater, Wastrilith | Water | Any | Planescape | PS 111 |
| Thork | Water | Sub-Trop/Trop | Any | FF 88 |
| Turtle, Giant, Snapping | Water | Any | Any | MAII 108 |
| Verme | Water | Any | Any | MAII 52 |
| Wattley | Water | Any | Any | MAII 55 |
| Will O' sea | Water | Any | Ravenloft | RVIII 121 |
| Worm, Mottled | Water | Any | Any | MM 364 |
| Zombie, Sea | Water | Any | Any | MM 373 |