Underwater Combat

(Based mainly on the D&D 5e rules for underwater movement and combat)

Each square of movement costs 1 extra square unless the creature has a swim speed.

To swim without sinking, a creature without a swim speed must make an Athletics check:

• DC 15 if wearing heavy armour or carrying a heavy load
• DC 10 if wearing medium armour
• No check otherwise

Creatures underwater have resistance to fire damage.

Melee attacks have disadvantage unless:

• Attacker has a swim speed, or
• Weapon is a spear, dagger, or similar

Ranged attacks:

• Disadvantage within normal range (unless the weapon is a crossbow, net, javelin, or similar)
• Impossible beyond normal range
• This applies to Aleric’s Sharpshooter feat
• Target pistol: Range 40'
• Rifled musket: Range 100'