This week’s post is part of the RPG Blog Carnival. This month the carnival is hosted by NukeTown.com, and the theme is “All These Worlds.” Be sure to check them out and see what others have shared on the topic.
The Monster Manual is full of useful creatures for your undersea campaign, and the easiest way to access these is to refer to appendix B in the Dungeon Master’s Guide, which lists coastal and underwater monsters. Below is a list of suggestions for expanding on those lists.

Aquatic and Amphibious Variants 5z1550
Many creatures can become sea monsters by giving them the ability to breathe underwater and a swim speed. Twig blights could become seaweed blights, while you could replace a frost giant’s greataxe with a trident and call it a sea giant. Be careful with some monster abilities though, an ocean basilisk could pose a real problem for characters who can’t breathe underwater.
Undead Creatures 6gmq
Most undead creatures can survive underwater, without any modification. Adding a swim speed is usually all that’s needed to make them effective threats. Ethereal undead, such as ghosts, can use their fly speed instead of a swimming speed, making them difficult to escape.
Constructs 72h15
Similar to the undead, constructs don’t need to breathe, so giving them a swimming speed is usually enough to make them useful. A homunculus might have a swimming tail instead of wings, while golems might be formed like sharks or dolphins, giving them a swimming speed and a reduced base speed. You can also replace some golem abilities with ones from other sea monsters; like giving a flesh golem tentacle attacks to replace its slam attacks.
Common sense if your greatest ally here — a stone golem is more likely to sink than swim.

When it comes to sea monsters, a little creativity goes a long way, and the Monster Manual serves as an excellent starting point for populating your campaign world.
What’s Next? 196u3f
What would you like us to cover for your undersea campaign next? Let us know in the comments below.
We recently asked about trinkets in your D&D game, and we’d love to hear your ideas, especially if you’ve got some ocean themed ones.
What trinkets have you enjoyed the most in your #DnD games?#RPG
— Rising Phoenix Games (@RisingPhoenixGM) November 12, 2018
Till next time, play good games!
Rodney Sloan
Rising Phoenix Games
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