Underwater Environments

As all readers of fantasy know, the ocean floor is home to numerous ancient submarine civilizations and dark, green realms of creatures half-man and half-fish. Your players may have heard tales of the mountains of sunken loot that have been collected there over the centuries, of such things as pearls the size of a man's head, of beautiful mermaids with green eyes and blue skin... If they should find some way to investigate these stories, how will you handle it? This section deals with methods for conducting underwater scenarios.

Breathing

The first major concern in underwater adventures is breathable air. Magic-users have the advantage in this area, as they have access to several spells that can solve the problem of submarine respiration. These include water breathing (which is also a druidical spell), airy water, shape change, or even wish, which might be made to work for the whole party (illusionists would use alter reality). They can also polymorph others into forms that can breathe water.

However, most non-magic-users will probably find the use of magic items or potions safer and more reliable. These include potions of water breathing or items like the helm of underwater action or the cloak of the manta ray (which help in movement as well as respiration).

The DM may also find it expedient to create such things as "air pills" or seaweed herbs that confer the temporary power to breathe water when ingested.

Most methods of underwater breathing are of limited duration, so most submarine adventures will be similar to dungeon adventures as regards time actually spent underwater. Players will have to get to their destination, accomplish their mission, and return in a matter of turns, rather than days or weeks as in other outdoor adventures.

If extended campaigns are desired, the DM will have to ensure that the players can acquire some sort of equipment or comestible that will allow them to stay underwater for an unlimited time.

See also Swimming and Drowning below.

Underwater Movement

There are two possible modes of movement underwater: swimming and walking.

Swimming is not possible in any type of armor heavier than leather (except magic armor), or when encumbered with more than 20 pounds of equipment of any type (add or subtract 1 pound for each 100 g.p. worth of Strength bonus or penalty). Though submersion in water makes everything "weigh less" due to buoyancy, actual mass of equipment is unchanged, and the same density that causes the illusion of less weight also causes a resistance to movement that slows it down considerably.

Therefore, movement (either swimming or walking) is the same as the speeds used in dungeons, even though underwater movement is "outdoors".

Average movement is a function of encumbrance in exactly the same ratios as in dungeon movement. Persons able to swim (due to lack of encumbrance, not innate natatorial ability) will be able to move vertically as well as horizontally, and at the same rate of speed. Remember that swimming persons are vulnerable to attack from every direction.

Characters encumbered with more than about 20 pounds of gear will be forced to walk on the floor of the ocean, lake, river, or whatever. They will have to negotiate underwater hills, coral outcroppings, shipwrecks, seaweed forests, etc., in the normal manner, i.e., they will have to go around or through them.

Characters equipped with a ring of free action or other magic item that confers the some power will be able to move normally and cover distance as if in the wilderness—that is, three times dungeon rate.

Swimming and Drowning

Unencumbered characters can swim underwater 100 ft. per round (or 10 ten-foot squares on the detail map)—in other words, 10 ft. per segment.

Holding Something and Swimming. Any person holding anything in one of his or her hands cuts swimming movement by 1/3.

Holding Your Breath. A character may remain underwater without drowning ("hold their breath") for a number of segments equal to his or her Constitution score. (1)

Thus, a character with a 16 constitution could remain underwater for 16 segments and could swim 160 feet, or 16 squares. After 16 segments (in that character’s case), the character would cease all activity and would begin to drown.

Drowning. Drowning takes 3-18 segments, and during this period the character can do nothing but writhe in panic (treat as stunned for combat purposes), though it is possible he or she could be dragged to safety. Such a saved character will suffer hit points of damage equal to the number of segments spent drowning. If not brought to air before the segments of drowning are up, the character is dead. If any cure wounds spell is cast on the character within 5 rounds of death, the character will revive to the 1 hit point level. One breath of air taken, for example, from a sealed scroll case or air bladder, will enable a swimmer to remain underwater for another time period equal in segments to his or her Constitution score. (1)

[Campaign Rules follow.]

Air Bladders. These are purpose made contraptions normally made from animal guts and leather meant to hold air. As it pertains to drowning, these special devices will hold 3 breaths of air. They cost 10 g.p. each and weight 20 g.p. empty in encumbrance weight. Any water or wine skin may be used as a improvised air bladder which will hold 1 breath of air.

Overcoming Buoyancy for Non-Aquatic Creatures. Without an air bladder, a creature needs at least 50-100 g.p. of metal weight (if gold = 50 g.p.) per 100 lbs. of body weight to achieve neutral buoyancy (neither sinking nor rising) in regular water because they are less dense in most cases. A creature may swim with up to 200 g.p. plus 10 g.p. per +100 g.p. in Strength Weight Allowance (or less)—negating their tendency to sink or float through effort. Each breath in an air bladder requires about 250 g.p. in metal weight to become neutral enough to swim slowly (as if Holding Something and Swimming). If more than this is carried, the creature can walk underwater as if Encumbered (including delay penalties and slower movement—see Equipment, Encumbrance).

[...]

Underwater Vision

Distance of vision will vary according to depth (available light) and obscuring objects. Basically, characters will be able to see objects and movement up to 50 ft. away in fresh water and 100 ft. away in salt water.

The depth limit of vision is the some as the distance limit: characters can see until they go below 50 ft. in fresh or 100' in salt water. Below this depth, vision will be obscured. You may wish to vary the distance as a function of depth to make this slightly more accurate, so that characters in fresh water could see 50 ft. at a depth of 10 ft., 40 ft. at a depth of 20 ft., and so on in segments of 10 ft. until vision is zero at 60 ft. of depth.

The same formula would apply to salt water, starting with 100 ft. of distance at 10 ft. of depth. Use of a light spell would allow vision up to 30 ft. distance regardless of depth, or add 10 ft. of vision to any distance shorter than 60 ft. (whichever is greater). The visual capability of a helm of underwater action will quintuple normal vision as pertains to both distance and depth.

Infravision and ultravision are useful underwater, and their distance limits are the some as in dungeon settings. There are some problems, however:

• Infravision users may become confused due to shifting currents and layers of different temperatured water, as water exchanges heat more slowly than air and therefore is of a less even temperature.
• Distance of ultravision is halved at 100 ft. depth and reduced to zero below 200 ft., as ultraviolet "light" does not penetrate beyond that depth in sufficient quantities for sight.

Other objects will also obscure vision. Seaweed or sea grass will reduce vision to 10 ft. or perhaps nil for those within it, depending on its density. Sea grass can be anywhere from 3 ft. to 30 ft. in height, while seaweed can take practically any size or shape the DM desires. In any case, shoals of either will totally obstruct vision, and anything may be hiding within! Schools of fish can also blind and confuse with their masses and quick movements.

Mud can also be a big problem, especially as pertains to combat on the bottom, where violent movement may kick it up in great clouds, totally blocking vision as long as the movement lasts and for 7-12 (d6+6) rounds afterwards, unless there is a current to carry it away. Even light sources cannot penetrate the muddiest water.

Underwater Combat

Underwater combat is difficult for normal land-born characters. Due to water resistance, effective use of crushing or cleaving weapons will not be possible—only thrusting weapons will be of any use (this means spears, tridents, daggers, stabbing swords, etc.).

Human-types will also be somewhat slowed underwater, so aquatic creatures will always get the first chance to hit, unless the human is armed with a significantly longer weapon than the opponent. Only those characters with free action ability (from a ring, helm or otherwise) will be able to move as if above water: they can use any type of weapon they could normally use, and they receive no reaction penalty. (2)

Combat Underwater

Combat in water environments has much to do with the amount of immersion of the combatants up to and including combat underwater.

Fighting in Water. If a character engages in combat while standing in water that is at least up to his knees but not higher than his waist, he does not enjoy any benefit to armor class due to Dexterity that he would normally have, and he must take a -1 penalty on all attack rolls (“to hit” and damage) in addition to any other penalties that may apply. If the water is more than waist high but not higher than the character’s chest, the penalty is -2. If the water is even higher, the penalty is -4. In no case however, can the damage from a successful hit be reduced to less than 1 point.

At the same time, any opponent attempting to hit a character who is immersed or partially immersed in water does so at the same penalty to attack rolls (even if the opponent is not immersed), reflecting the fact that a smaller portion of the character’s body is vulnerable to a weapon blow.

Native Swimmers. Of course these penalties do not apply to a creature that is native to an aquatic environment, assuming that the creatures can strike freely either above the water or below the surface. For a creature with a native swim movement rate, the latter two penalties are reduced by one-half and the penalty for attacking in water up to waist deep does not apply.

Underwater Combat. Underwater combat is difficult for normal land-born characters. Due to water resistance, effective use of crushing or cleaving weapons will not be possible—only thrusting weapons will be of any use (this means spears, tridents, daggers, stabbing swords, etc.). Non-native swimmers will also be somewhat slowed underwater. Each round, they will suffer a delay of 1d6 segments before any action may begin.

• Underwater Combat Penalties for Non-Native Swimmers: Movement at 1/3; Suffers Delay (+1d6 segments to all major actions); -4 to-hit and damage (minimum 1 point of damage); No Dexterity to AC; Only thrusting or natural weapons may be used.
• Underwater Combat Penalties for Native Swimmers (Creatures with a listed Swim Movement Rate): -2 to-hit and damage (minimum 1 point of damage); Only thrusting or natural weapons may be used.
• Underwater Combat Penalties for Aquatic Creatures: None.

Nets

Nets will prove useful as an adjunct to thrusting weapons underwater, especially if both of the combatants are swimming. There are several ways nets could be used.

Two or more characters could stretch a large net between them and foul up attackers or combatants by maneuvering it so that their opponents become entangled therein. This is most effective vs. charging or unsuspecting opponents, who will have less chance of avoiding it.

Nets wielded single-handedly in combat must be weighted. As the net is thrown, it is given a slight horizontal spin. The spin causes centrifugal force to move the weighted ends out, which keeps the net open and untangled. If thrown correctly, it will slow and stop spinning as it arrives at its target, the weights then pulling the net down over the victim. Nets can be thrown one foot for every point of the thrower's Strength. Underwater races can throw nets an average of 15 ft., sahuagin 20 ft. Weighted nets can also be dropped upon non-swimmers on the ocean floor to drag them down or incapacitate them. Some battle nets have little hooks or barbs attached at every intersection to ensure that targets will be unable to escape easily.

All of the undersea races use nets, particularly aquatic elves, locathah, and mermen; the most adept of all are the sahuagin. They will often set ambushes involving many small nets or one huge net several hundred feet in diameter. These may be concealed in seaweed or left floating near the surface, disguised as something else. The sahuagin are masters of combat net-work as well, and will often fight with a net in one hand (to entangle and confuse) and a short, jabbing trident in the other.

The underwater combat net is a difficult weapon to use, and player characters who attempt it will do so at -4 to hit (unless they undergo extensive training and choose the underwater net as a weapon of proficiency. Such training must take place underwater).

Other Weapons

Except for certain specially-made crossbows, use of missile weapons is generally impossible underwater. Special crossbows which will function underwater can be made by knowledgeable bowyers for ten times the normal price. Effective underwater range of these will be one-half normal (dungeon distances).

If characters intend to go somewhere where normal missile weapons could be of use (like the great air-filled domes of Atlantis), bows and missiles must be kept dry. This is doubly true of such things as scrolls and books, of course.

Using Spells Underwater

Spell use underwater will be limited to the some ranges and distances as in dungeons.

In addition, there are problems with spell preparation, as many material components will be altered by or will not work correctly underwater.

Some spells will be altered in effects as well. Fire-based spells (such as fireball) will not function at all underwater (except within the radius of an airy water spell). Electrical spells will be conducted to the entire surrounding area - a lightning bolt will behave as a fireball, etc. As Dungeon Master, you can alter whatever spell preparations or effects you deem necessary and reasonable.

Underwater spell use

The following spells cannot be cast or will not function underwater (* spells that can be cast and will function within the bounds of an airy water spell):

Cleric:

3rd level - speak with dead*

4th level - lower water, speak with plants*

5th level - atonement*, flame strike, insect plague

6th level - aerial servant

7th level - control weather, wind walk

Druid:

1st level - predict weather

2nd level - fire trap, heat metal (though its reverse, chill metal, will work), produce flame*

3rd level - call lightning, pyrotechnics*, summon insects

4th level - animal summoning I, call woodland beings, produce fire*

5th level - animal summoning II, control winds, insect plague, pass plant, wall of fire

6th level - animal summoning III, conjure fire elemental, fire seeds, weather summoning

7th level - Chariot of Sustarre, control weather, creeping doom, fire storm

Magic-user:

1st level - affect normal fires*, burning hands*, find familiar

2nd level - pyrotechnics*

3rd level - fireball, flame arrow*, gust of wind

4th level - fire charm, fire shield - hot flame* (the cold flame version of this spell will still function), fire trap, wall of fire, distance distortion

6th level - control weather, guards and wards*, lower water

7th level - cacodemon*, delayed blast fireball

8th level - incendiary cloud, polymorph any object*

9th level - meteor swarm

Illusionist:

1st level - wall of fog*

3rd level - illusionary script*

7th level - first level magic-user spells: affect normal fires*, burning hands*

The effects of the following spells will be substantially altered when cast underwater:

Cleric:

6th level - part water: this spell can be used to form a "tunnel" through deep water, no wider than 10 ft. in diameter.

7th level - earthquake: effects are as follows:

Terrain: Underwater—causes shock waves stunning all within range who fail to save vs. death magic for 5-20 rounds.

Druid:

7th level - conjure earth elemental: an earth elemental conjured underwater will have to stay in the sea, lake, or river floor from which it was conjured, and cannot venture into the water. However, it may still assault creatures or constructions resting on or in the ground.

Magic-user:

3rd level - fly: this spell will enable the recipient to swim easily at any depth desired, even if encumbered or normally too heavy to float. Maximum speed is 9".

3rd level - lightning bolt: underwater, this spell resembles a fireball as pertains to area of effect. Instead of a stroke, the electrical discharge takes the form of a 2" radius sphere, centering on the point where a stroke would originate were the spell cast above water. All those within the sphere will suffer the full effect (saving throw indicates one-half damage).

4th level - ice storm: the icy hail formed by this spell will be very large but weak in downward force, inflicting only 1-10 hit points of damage before floating to the surface. Sleet will melt instantly and have no effect.

4th level - wall of ice: a wall of ice can be formed underwater, but it will immediately float to the surface and bob about like an ice floe.

5th level - conjure elemental: air and fire elementals cannot be conjured underwater at all. Earth elementals can be conjured only as described above under conjure earth elemental. There is no problem about conjuring water elementals, of course.

6th level - Otiluke's freezing sphere: this spell is extremely dangerous to the caster if invoked in its first manifestation while submerged. The globe of absolute zero matter, when formed underwater, will instantly freeze the water around the caster into a block of ice of a volume equal to 50 cubic feet per level of the caster. This will last a number of rounds equal to the level of the caster. Unless immediate aid is forthcoming, the magic-user will suffocate (the ice-entombed magic-user will immediately float to the surface, of course) .

6th level - part water: see 6th level clerical spell part water (above) for comments on this spell.