Aquatica Rules For Underwater Adventures

These rules are meant to make underwater combat more fun, without making it easier or harder. Some mechanics have been added to provide more tactical options. Others have been changed from all-or-nothing outcomes into more dramatic struggles with many shades of success or failure.

If you find vertical positioning to be tedious to track on a traditional top-down battle map, try switching to a side-view map while underwater!

Movement While swimming, each foot of movement costs 1 extra foot (2 extra feet in difficult terrain), unless a creature has a swimming speed. The Dash action cannot be taken underwater by a creature that lacks a swimming speed.

Breath A creature can hold its breath for a number of minutes equal to 1 + its Constitution modifier (minimum of 30 seconds). When a creature ends their turn breathless and underwater they must lose 1 hit die or fall unconscious. When an unconscious creature starts their turn underwater, they lose 10 health. A creature immediately loses their breath if they are critically hit or if they fall into water unexpectedly.

Communication Most languages cannot be spoken underwater. Aquan can be readily spoken and understood, but otherwise the only means of communicating underwater is with rudimentary sign language.

Casting When a creature casts a spell that requires verbal components, they exhale their remaining air. After they finish casting, they become breathless.