Basic 1: Characters mentions penalties for acting underwater. What are they?
Currently, there are no unifed rules for this in 4e. The 3e rules were bad – playtesters who had experience with scuba, including a guy trained in hand-to-hand combat by the Marines, warned us off reusing those in 4e. So I wouldn’t use ’em. In 4e, I suppose it will be its own PDF someday. Until that day, apply the extra movement-point costs on p. B387 and the penalties for bad footing on pp. B547-549. Drag is a complicated question, as it depends on cross-sectional shape, so it’s difficult to generalize about its effects on melee damage . . . really, each weapon will need its own new rating.
