Undersea Adventures in D&D, Part 2

The Player’s Handbook, Dungeon Master’s Guide, and Monster Manual all provide great resources for undersea or ocean-based D&D campaigns. Last week we offered an Undersea Guide to the Player’s Handbook. Today I’ll run through the Dungeons & Dragons Dungeon Master’s Guide to help you dive into your undersea adventures.

Undersea Fantasy

The Flavors of Fantasy section in chapter 1 includes a short coverage on swashbuckling fantasy, which offers some inspiration. An undersea campaign might just as likely contain elements of dark fantasy, sword and sorcery, or epic fantasy too.

Undersea fantasy might focus on the otherworldly aspect of the ocean, giving special attention to the wonders of this new world, or emphasizing the alienness of the sights and creatures found there. The sea has a clearly defined border, and crossing this threshold for the first time is almost always a significant event. On top of that, many things we take for granted are not readily available or don’t work in the deep, such as fire, paper, ink, drinkable water, or air. Gravity is less pronounced, and capable swimmers can move in three dimensions, much like flying creatures can do above the waves. Take these aspects into account when building your own undersea campaign.

Planes

The Plane of Water section in chapter 2 describes the elemental plane of the same name, which offers an excellent setting for your campaign as well as inspiration for one set on the Material Plane.

Adventure Environments

Chapter 5 contains a wealth of information that can be applied to undersea adventures with a little work. The Underwater section is particularly noteworthy and includes a table of random undersea encounters, expanded swimming rules, and rules for underwater visibility. The Sea section includes rules for navigation, weather at sea, visibility, and owning a ship, along with a table of random encounters at sea and statistics for airborne and waterborne vehicles.

Magical Items

Notable magical items include the apparatus of Kwalish, cap of water breathing, cloak of the manta ray, folding boat, gloves of swimming and climbing, mariner’s armor, necklace of adaptation, potion of water breathing, swan boat feather token, ring of swimming, ring of warmth, ring of water walking, and trident of fish command.