Aquatic Terrain
Aquatic terrain can be one of the least hospitable to PCs because most can’t breathe underwater. The ocean floor holds many marvels, including undersea analogues of any of the other terrain elements described in this chapter, but if characters find themselves in the water because they were bull-rushed off the back of a transport ship, the kelp beds or volcanic vents hundreds of feet below them don’t matter. The most common rules sections to reference when using aquatic terrain are Suffocation and Drowning (see page 404) and Underwater Combat (see page 405). The rules for swimming with the Athletics skill (see page 137) are also critical for many creatures operating in an aquatic environment.
Source
Core Rulebook pg. 396
Lakes and oceans simply require a swim speed or successful Athletics checks to move through (typically, DC 10 in calm water, DC 15 in rough water, DC 20 in stormy water, and DC 30 in maelstrom water). Characters need a way to breathe if they’re underwater; lacking that, they risk drowning. When underwater, characters can move in any direction, including up and down. Source Core Rulebook pg. 396 |
At certain depths, the pressure of the surrounding water becomes so great that characters might be affected as if they were in a thick or severely thick atmosphere (see page 396), even if they can breathe underwater. Source Core Rulebook pg. 396 |
How far a character can see underwater depends on the water’s clarity. As a guideline, creatures can see 4d8×100 feet if the water is clear and 1d8×10 feet in murky water. Running water is always murky, unless it’s in a particularly large, slow-moving river. It is hard to find cover or concealment to hide underwater (except along the sea floor). Source Core Rulebook pg. 397 |
