Underwater Combat

An oft-neglected, but fascinating, area for adventure is that great and mysterious realm that lies beneath the waves. Here, ancient civilizations, green and dark, lie waiting to be discovered. Vast treasure hordes are said to lie scattered and open on the murky bottom. Creatures, fearsome and fanciful, rule kingdoms unknown to man. Many are the mysteries of the ocean, but, to solve them, players must deal with some unusual problems.


The biggest problem facing characters underwater is, naturally, breathing. Before any kind of underwater adventure is undertaken, they have to find some way to stay underwater for long periods. Characters can use magical spells or devices; they can use water breathing potions; they can even polymorph themselves into underwater creatures (although this might lead to other, unexpected problems). If none of these solutions seems workable, the DM can provide oxygen-supplying seaweeds or kelps the characters can eat.

Without some method of breathing underwater, the characters are going to have a very short adventure! Rules for holding one's breath (a short term solution, at best!) and drowning can be found in the
Player's Handbook .


There are two basic ways to move in water--swimming or sinking like a stone and walking on the bottom. Rules for
swimming can be found in the Player's Handbook. In rare cases, player characters may be able to find and use trained

mounts such as giant seahorses.


One major limitation of underwater combat is the lack of available light. In fresh water, vision is limited to a base of 50'. This is reduced by 10' for every 10' of depth. Characters exploring the depths of a murky lake, 50' below the surface, could see about 10'. Below this, the darkness would close in about them.

In salt water, which has somewhat less algae, the base extends out to 100', modified for depth in the same way as fresh water.

Natural and Artificial Light

The vision guidelines above assume a bright sunlight day on the surface overhead. On overcast days, the distance a character sees can be reduced by half or more. On moonless nights a character's range of vision is virtually nil.

Artificial light sources function underwater (although players will have to think fast to keep torches and lanterns lit). Artificial light sources illuminate half the space under water that they would light on the surface.

Obscured Vision

In addition to low light, vision can be obscured by seaweed, sea grass, and kelp forests. These hamper vision in much the same way as thick brush on the surface.

Schools of fish with their often silvery scales can reflect and scatter light in hundreds of different directions, creating a shining cloud of confusion. Even without the reflection, their darting forms obscure an area.

Finally, the ink from a giant squid, or even mud stirred up from the bottom, have all the effects of a darkness spell. Infravision and light have no success penetrating such murky waters.


Infravision functions underwater, though not with the same efficiency as on the surface. In no case does it extend past the normal ranges allowed in dungeons. In addition, the sheer alienness of the environment makes it difficult for the character to be certain of all he sees.


The greatest factor in fighting underwater is overcoming the resistance of the water. Even though a weapon still retains its mass and density, the resistance of the water greatly weakens the impact of any blow. Thus, only thrust weapons can be used effectively underwater (except for those possessing magical items that enable free action).

Thrown and hurled weapons (except nets) are useless underwater. Of the missile weapons, only specially made crossbows can be used effectively underwater. Even so, all rangers on these weapons are reduced by half.

Nets are particularly effective in underwater combat. They tend to remain spread once opened, and characters should find them useful for close-in combat. Properly weighted, nets can be thrown by tossing them with a slight spin, so that the force of rotation keeps the lines taut. The range is very short, only 1' for every point of the thrower's Strength.

Combat Problems of Surface-Dwellers

In combat, surface-dwellers suffer special disadvantages when fighting the races of the sea.

Being unaccustomed to the water resistance and changed in apparent weight, surface-dwellers add four to their initiative tolls in hand-to-hand combat. This does not apply to missile fire or spellcasting. Surface-Dwellers also suffer a -4 penalty to their attack rolls, due to the slowness of their movements.

Underwater Magic

Spells are also affected by the underwater world. Not surprisingly, fire-based spells have no effect unless cast in an area of free oxygen (such as a domed city).

Electrical spells conduct their energy into the surrounding water. Thus, a lightning bolt originating 60' away from the caster acts like a fireball at the point of origin.

Spells affecting forces of nature not normally found underwater have no effect--call lightning, for example. Spells that summon or command creatures not native to the depths are also pointless.

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