Don't Go In The Water

Printer-friendly version

In role playing games most of the challenges stem from puzzles, skill challenges, and combat.  The Hazardous Environments and Weather series was conceived to provide game masters details on environment related challenges.  Each article in this series has a theme this one focuses on all things water

Note that life jackets are an oft overlooked equipment item from the basic equipment list.  It is appropriate for the boats that are available for player use to be stocked with life jackets.  It’s almost certain that insurance carriers will require them on commercial vessels transporting passengers.

Tidal Bore

Tidal bores require particular geographic features in order to occur.  They must have a large tidal range, at least six meters between high and low water and a narrow inlet.  When the strong tidal surge forces its way into a river or bay it creates a large wave or waves sweeping in against the current of the river or bay.  A tidal bore’s identifying features are turbulence and a roar.  Large bores can be hazardous to shipping (requires a ship handling check for boats).

The occurrence of this phenomenon is by referee fiat and could be used as an extra wrinkle to an otherwise placid river crossing or to spice up a combat taking place in a shallow inlet.  A tidal bore can travel between 6-15 meters/turn (1d5 + 10).  A referee can assign a strength value to the tidal bore or roll a d5.  Any character caught in turbulence must make a DEX check modified by 10% times the strength of the tidal bore to keep his feet.  If a character loses his feet he takes damage for one turn from being rolled in the turbulence at 1d5 times the strength of the bore.  A successful STA check cuts the damage in half.  Characters that lose their footing will be pushed along with the wave, requiring a STR check just to swim in a direction desired by the player.


Whirlpools are not normally powerful and are usually produced in narrow shallow straits with fast moving current or at the foot of a powerful waterfall.  Powerful ones are known as maelstroms.  Among the most powerful maelstroms on Earth, speeds of 37 km/h (23 mph) have been observed.  The danger is to swimmers not to ships.  Tales of large ships being sucked down are entirely works of fiction.

Should characters ever find themselves in water near a maelstrom or whirlpool they should make a STR check at the time they would first come within the area of effect of the vortex.  On a failed check they are pulled into the vortex and have 1d5 turns before being pulled under.  On the turn after a character first feels the vortex and fails a STR check he can make a second STR check to swim out or be sucked deeper.  After that he’s too deep to swim out and requires rescue by rope or branch.

A character pulled under will be churned in the water for 1d5 combat turns taking 1d5 STA hits per turn.  He must hold his breath for the entire experience but if reduced to 0 STA he has drowned and will require immediate medical attention.  Any character race with lungs will require basic rescue breathing technique that all characters are assumed to know.  The game procedure to preform rescue breathing is to make a STA check against the unmodified score for each turn of rescue breathing to revive the character. If a medic is on hand revival is automatic with rescue breathing and shot of stimdose.   Dralasites simply require basic first aid (stimdose) since they have no lungs to fill with water.

Use of a rope provides a character a +20 bonus to the STR check to avoid being sucked into a maelstrom’s vortex.  A character with a life jacket will surface one turn after being sucked under.  A dralasite with foresight to prepare can spend 10 minutes inflating his body with air pockets that will act like a life jacket.

Water Spout

Not normally as strong as their land counterparts, water spouts are best described as non-supercell tornados over water.  They have long been recognized as a serious threat to swimmers, boats, and helicopters. Water spouts are more common in the tropics but have been observed in temperate latitudes as well as in conjunction with lake effect snow.

A water spout occurs when an updraft column of swirling air forms over water.  It does not suck up water but instead condenses water droplets within the column from the surrounding air.  Its life cycle follows five stages.  A character with the appropriate environmental or meteorological skill has a chance to identify the formation of a water spout by skill check during the first three stages but after that it’s obvious what is happening.  First stage is a dark spot on the water.  The second stage is a spiral pattern on the surface of the water.  The third stage is the formation of a spray ring.  The fourth stage is the development of the visible condensation funnel.  The final stage is decay.  A referee has a lot of flexibility in the length of each stage.  If the time scale is combat turns then each stage can take several turns.  If the time scale is ten minute turns then the water spout can completely form and decay in that time frame.  The shortest stage is the decay stage.  I would recommend keeping the first three stages brief and getting to stage four which is more dramatic, allow for a variable amount of time for the condensation funnel to last from minutes to hours (d10 minutes or 1-2 hours).

When using the water spout to challenge and threaten player characters, use the grenade bounce table to move it each turn a variable distance 2-20 meters.  Characters and boats within 10 meters take 1d10 STA or structural points of damage.  Characters or boats hit by the water spout take 2d10 STA or structural points of damage. Helicopters suffer the above effects as well and require a pilot skill check.  If the check fails, the helicopter spins out of control losing 40m/turn of height (requires a skill check each turn to recover).  Helicopters hit by the water spout take double damage and the pilot skill check is -20%.

Rip Tide

The proper name is rip current, which is a strong current flowing seaward from the shore.  To escape a rip current a swimmer must swim perpendicular to the current or parallel to shore.  The rules for swimming and swimming endurance should be reviewed from the rule book though a character with a lifejacket will survive automatically.  This challenge is suitable along ocean beaches but a planet without a moon will not have a tidal effect making a rip current unlikely.


Hurricanes are known by several names depending on their location or strength:  typhoon, tropical storm, cyclonic storm, or tropical depression. They originate in the tropics and can move great distances in a matter of days.  The area of a hurricane is divided into the dangerous semicircle and the navigable semicircle based on direction of travel with the right half being the most destructive.

The effects of a hurricane include large waves, heavy rainfall, storm surge, lowered ocean surface temperatures (after it passes), flooding, tornadoes, geomorphology (reshaping the geography of coastal areas), and defoliation of tree canopies as well as stripping bark and limbs which fuels forest fires (one such occurrence led to a 3 month forest fire in 1989).

A hurricane is suitable as a backdrop for an adventure with adjustments made for effects and closeness of the hurricane.  It is very likely the players will have prior warning especially on any settled world with satellites.  Communication networks will actively keep the population apprised of the situation and an emergency warning from the government is to be expected before the worst effects hit.  As a backdrop for an adventure it can add extra flavor and complications.  High winds can reduce visibility and degrade the performance of certain weapons.  Storm surge can complicate combat or a rescue.  Loss of power and other services could hamper the player characters in the pursuit of their mission.

She Fell In – Caitlin Turpin (Alice-chan on Deviant Art)

Tidal Wave/ Tsunami

Tsunami is Japanese for harbor wave.  Tsunami’s occur when large volumes of water are displaced by earthquakes, mudslides, glacier calving, underwater volcanic eruptions, underwater explosions, or a comet or meteor strike in the ocean.

An early warning sign is the rapid withdrawal of water from the shore line.  Within minutes the wave will rise up like a wall as it transverses shallows and flood kilometers inland.

Tsunamis are incredibly destructive killing hundreds of thousands and destroying property indiscriminately. For this reason they are unsuitable to unleash directly on the player characters but can be used as a plot device.  If player characters are on a ship when a tsunami hits they can be driven inland and the ship beached on a hill, building or some other geographic feature.  If far enough out at sea the ship may whether the wave but the players characters may be called on to render assistance to survivors on shore.  A classic option but likely unrealistic, would be if a ship was capsized by a tidal wave, as in the movie “The Poseidon Adventure”, requiring the players to effect their escape from the ship before it eventually sinks.

Storm Surge

Storm surge occurs when strong storm winds cause the oceans tide to pile up higher than the normal tide and flood onto land.  The area of flooding will largely be determined by the topography of the coast but a referee can roll 1d10 up to 5d10 for the number of meters that the surge floods.  Or if his judgment is that the topography of his map dictates a particular effect, he can simply go with his best judgment.

The effect will flood coastal areas and damage buildings and vehicles.  Do not neglect the effects of salt water to cause long term problems with vehicles and equipment.  Characters caught in the flooding of the storm surge could be required to make a DEX check to maintain their footing or be swept 2-10 meters either inland or out to sea (determine direction randomly at first then alternate direction each turn).  If they have been swept off their feet they need to make a DEX check at -10 each turn to regain them and cannot act normally until they do.  Alternately a character may make a RS check to grab a fixed object and halt his movement then the next turn he may make DEX check at +10 to regain his feet.  In addition any character that has managed to grab a fixed object can opt to shoot a weapon at -10 instead of standing immediately.  If swept out to sea they must swim for shore but risk being driven into objects on land with the next surge (1d10 STA hits if this happens).

This challenge is less of a threat and more of a hindrance to the character.  It’s best used as an added complication while other things are happening like combat.

Rogue Wave

Once thought to be myth, rogue waves are now known to occur in all the world’s oceans, seas, and in the Great Lakes. They typically occur far out at sea spontaneously and move against the expected flow of the prevailing currents.  Waves in mid ocean storms can range from 7-15 meters but a rogue wave can reach 35 meters (115 ft.).  Ships encountering such waves are unlikely to survive due to the pressure the breaking wave exerts (142 PSI).  It would be expected that a ship caught by this wave will sink in minutes.

In game terms, there would be little to no notice before the wave struck and the characters on board a ship would have up to 10 minutes to escape.  Since it is bad form to just kill player characters without giving them a chance to survive, I recommend giving some notice even if it’s a non-player character screaming into the intercom, “Rogue WAVE!”  The event can also be foreshadowed by a crusty old sailor telling tall tales about killer waves to put the players on notice.

There is no point in giving a damage statistic for what the wave will do other than simply saying that it sinks ships, period.  Then again, miracles have been known to happen so giving a large ocean going ship a percentage chance to survive is probably not inappropriate in a role playing game.  However, the chance should be small, around 5-25%.  The rogue wave is a drastic measure and probably best reserved as a plot device instead of a real challenge.  Characters escaping a ship going down in this situation will be scattered about and unlikely to link up at all and this will result in a split party.  One option would be for the player characters to respond to a ship in distress and when they get there by helicopter the wave takes down the ship and the players must rescue crew in the water.


Some weather and environment effects are suitable as an added layer of challenge for the player characters during the course of a regular adventure. Others result in such a level of devastation that they are only suitable as plot devices and backdrop for the adventure.  They are all presented here as tools for the game master to change up a game or throw a monkey wrench at the players.  So often the challenge in a game is combat based but dealing with hostile weather can play a role as a challenge especially when it’s necessary to limit violence, particularly when gaming with children.