I was born in the water, daughter of the moon and the sea.
No matter where I seem to be in the world, the ocean always calls me home. East or West coast, frigid, Atlantic waters or warm, tropical seas, the sound of the waves and the endless blue horizons feed my heart. For this and many other reasons, World Oceans Day is near and dear to my heart. To celebrate the day, I am going to showcase some fantastic water based monsters for your Fifth Edition Dungeons and Dragons game!
Content Warning: Some descriptions may be graphic. Some monsters do have telepathic, mind control powers or may deal psychic damage.
Averaging at 135 hit points and with a challenge rating of CR10, this large aberration is no joke! It seeks to dominate the minds of unwitting creatures in the aims of gaining thralls, using its probing telepathy. In addition to its ability to multi-attack with Tentacle, Tail and Enslave actions, the Aboleth also boasts its share of legendary actions that it regains each turn: Namely Detect, Tail Swipe and Psychic Drain! Our party had to face off against a baby Aboleth once, and even as a young and inexperienced monster it was quite the threat!
This gargantuan elemental is not something you would want to face off against as a player! Averaging 264 hit points, with its physical Attributes all above 20, you want to be careful as a GM when introducing this creature to your party. The Elder Tempest is a living thunderstorm, capable of legendary actions, including Lightning Storm and Thunderous Slam. I, for one, would love to see a sailing ship and crew face off against the Elder Tempest in search for safer shores. I just wouldn’t be confident any ship, its crew, and even a party of adventurers would hope to reach land in tact!
Amphibious, Multi-attack, Legendary Resistances, Legendary Actions, Lair Actions, and Regional Effects. What can’t this Gargantuan dragon do? I love that its lair actions are all focused on controlling the water. Whether it is creating a scalding geyser of ocean water, flooding the area it is standing in or causing the water itself to attack and deal damage to the adventurers, this dragon is truly in its element in the water! I also enjoy the regional effects that their stat block takes into account such as flooding, which can affect how other sea creatures act, and transporting creatures from the elemental plane of water. May the heavens have mercy for any adventuring party that meets tooth and claw against Leviathan, for it is likely that none shall survive the encounter.
Morkoth are cruel aquatic predators with gnashing teeth that are visible even when their mouths are closed! The physical description of the Morkoth is the stuff of underwater nightmares, with large octopode tentacles, a squid like beak, and a barnacle encrusted hard shell encased with treasure chests and other trinkets! While their bite can be deadly, their true power is in their ability to hypnotize their prey to enter their labyrinth of a lair. And once someone is lured in, they will have a difficult time getting back out!
This large fiend has several impressive abilities. While not a legendary creature by design, it has abilities that will keep its survivors talking about its wiles for generations. While Sharp teeth and claws are pretty standard is a clear threat, and its Undertow action is downright dangerous, its most interesting ability may be Corrupt Water. At the start of each of its turns any exposed water can become befould. This will lightly obscure the water and it will remain this way until it evaporates. Think about that. A fight between your party and the Wastrilith can happen and then weeks later the water still might not be good to drink, use to water crops or swim in. If it is raining when your battle happens, what are the long term effects of this ability? Could it possibly poison entire landscapes in its wrath? What a chilling thought.
This of course is just a small sampling of the potential dangerous that may lurk within the briny deep of your TTRPG setting. And whether its squaring off against the Morkoth or running for dear life from an angered Elder tempest, ocean monsters are a sure fire way to spice up any adventuring parties travels. Just be sure to remind them that the Aboleth isn’t real and can’t hurt them (as far as we are aware, at least),