Water-Based Gameplay

Water in Dustriders

To clarify a few things with how gameplay surrounding water works, these are the rules surrounding water gameplay in Dustriders. Nautical campaigns can potentially happen, and while water is not the core focus of a lot of gameplay within Dustriders, the rules from D&D 5e carry over with a few alterations. Some of this is adapted from other homebrew sources.

Swimming

Unless you have a swim speed, your movement speed is halved. Some equipment, such as diving flippers grant you a swim speed, but half your movement speed on land. It takes 10 minutes to equip and unequip diving flippers.
Swimming in Armor

Light Armor: You are not impeded by Light Armor in Dustriders while swimming.

Medium Armor: Requires a DC 10 Strength (Athletics) check each round. Failure means you have a speed of 0 for that round.

Heavy Armor: Requires a DC 15 Strength (Athletics) check each round. Failure means you have a speed of 0 for that round and you sink 10 feet.

Superheavy Armor: Requires a DC 20 Strength (Athletics) check each round. Failure means you have a speed of 0 for that round and you sink 20 feet.

Long Distance Swimming

It’s possible to become exhausted during prolonged swimming. You roll a Constitution saving throw (DC 10) for each hour spent swimming. Failing this saving throw will result in one level of exhaustion for the character. The rules place a hard limit on swimming for eight hours, specifically stating a character cannot swim for that long.
Characters with swimming speeds can swim all day without penalty.

Falling into Water

If unintentionally falling into water from a distance greater than 30 feet, players may as a reaction roll an Athletics or Acrobatics check against a DC15 to halve the damage taken. Otherwise, if falling into water from a distance less than 30 feet, players won't take damage from hitting the water.

Underwater Combat

You roll melee weapon attacks with disadvantage underwater except in the following cases:

The character has a swimming speed.

Riding a mount that possesses a swimming speed does not cancel the disadvantage of your underwater melee weapon attacks.

The weapon is a dagger, javelin, shortsword, spear, or trident.

Ranged weapon attacks automatically miss if the target is beyond the weapon’s normal range. For example, a longbow would automatically miss beyond 150 feet since its range is 150/600. You roll ranged weapon attacks with disadvantage underwater unless the weapon is a crossbow, net, dart, javelin, spear, trident, or other thrown weapon.

Firearms will only be able to fire one shot while underwater and will automatically jam after firing unless they have the Flechette or Underwater Firearm properties.
Any creature fully immersed in water will resist fire damage.
Underwater spell attacks roll as normal without disadvantage. Only weapon attacks get disadvantage.
If you want to cast a spell underwater that requires verbal components, you can do that. Doing so means you’ll stop holding your breath and start suffocating. In D&D 5e, suffocating means you die in a number of rounds equal to your Constitution modifier. It’s extremely risky to cast a spell in this way and begin suffocating. Casting Water Breathing will allow you to freely cast spells with verbal components underwater without suffocating.

Drowning, Suffocation, and Holding Breath

Some equipment grants you water breathing for a set amount of time or makes it easier to hold your breath. An Aqualung, a piece of equipment grants you 1 hour of breath while underwater.
Holding Your Breath

You can hold your breath for a number of minutes equal to 1 + your Constitution modifier. If you have a Constitution score of less than 10 you can hold your breath for 30 seconds. At that point, you fall unconscious.

When you don’t have time to prepare to enter the water, like if you were surprised, the time that you can hold your breath is halved, to a minimum of 30 seconds.

Once unconscious, you can survive for a number of rounds equal to your Constitution modifier (minimum of 1 round.) At that point, you drop to zero hit points, begin to drown and must start making death saving throws.

When drowning, a you cannot regain hit points or be stabilized until you are once again able to breathe.

When in combat, if you take any action other than the dodge action, at the end of combat you lose 1 minute from the time that you can hold your breath. For a long combat, for every 10 rounds you lose 2 additional minutes.

When you are hit, you must make a DC 12 Constitution saving throw. On a failure you lose an additional 30 seconds from the time you can continue to hold your breath. If it was a critical hit, you must instead make a DC 20 Constitution saving throw. On a failure you loose your breath and fall unconscious.

Underwater Visibility

If you do not have the Underwater Vision feature, either from your chosen race or a piece of equipment, your vision will be severely limited. You will only be able to make out blurred shapes and shadows. Without Underwater Vision, you roll perception checks with disadvantage.
Without 'Underwater Vision'
Clear Water, Bright Light: 60 feet to notice an encounter or see a target
Clear Water, Dim Light: 30 feet to notice an encounter or see a target
Murky Water, Dim Light: 10 feet to notice an encounter or see a target
With 'Underwater Vision'
Clear Water, Bright Light: 180 feet to notice an encounter or see a target
Clear Water, Dim Light: 90 feet to notice an encounter or see a target
Murky Water, Dim Light: 30 feet to notice an encounter or see a target