Underwater Combat

Special rules apply when fighting in an aquatic environment.

A creature that doesn't have a swimming speed has disadvantage on melee weapon attack rolls unless the weapon is a dagger, javelin, shortsword, spear, or trident.

• Ranged weapon attacks automatically miss targets beyond the weapon's normal range
• Even within normal range, the attack roll has disadvantage unless the weapon is a crossbow, net, or a weapon that is thrown like a javelin (spear, trident, dart)

Creatures and objects fully immersed in water have resistance to fire damage.

A creature can hold its breath for a number of minutes equal to 1 + its CON modifier (minimum 30 seconds). When out of breath, a creature survives for a number of rounds equal to its CON modifier (minimum 1 round). At the start of its next turn after that, it drops to 0 HP and is dying.

Each foot of movement while swimming costs 1 extra foot (2 extra in difficult terrain) unless a creature has a swimming speed. The DM may call for STR (Athletics) checks in rough water.