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Archives of Nethys

Archives of Nethys

Pathfinder RPG (1st Edition) Pathfinder RPG (2nd Edition) Starfinder RPG

Rules Index | GM Screen | Player's Guide
Chapter 1: Gamemastery Basics / Running Encounters / Special Battles and Movement

Aquatic Combat

Source Gamemastery Guide pg. 15
The rules in the Core Rulebook are fairly generous to allow high-action battles underwater. Two significant challenges for non-aquatic creatures are breathing underwater (or holding their breath) and lacking a swim Speed. It’s often best to save aquatic adventure until higher levels when PCs can get magical solutions for these problems, but you can instead give out such magic early, since it’s not easy to exploit in land-based adventures the way flight magic can be. As with flight, dispelling can be deadly if someone relies on magic to breathe underwater. It’s generally best to avoid having enemies who can breathe underwater dispel the water-breathing magic aiding PCs. Though PCs might be able to use air bubble and quickly cast water breathing again, having this happen repeatedly can be frustrating, and being forced to prepare an extremely high-level water breathing spell to avoid it isn’t much fun either. Lacking a swim Speed is easier to deal with, except for characters with poor Athletics, who might need to strategize around their shortcomings. The DC to Swim underwater shouldn’t be very high—typically 15, or 13 in calm water.

When someone gets knocked out underwater, they usually float up or sink down. You decide based on their buoyancy; most adventurers carry a heavy enough load to sink.

When one group is in water and another outside it, note that the aquatic combat rules for attacks apply when either party is in water. You might judge that a character in the water is concealed against someone outside it due to distortion, and vice versa.