Swords & Wizardry House Rules: Swimming and Drowning

Bodies of water and water hazards are common in Dungeons & Dragons, but the original rules and most retroclones, including Swords & Wizardry, have no rules for how to handle swimming and the risk of drowning. I'm not a fan of adding to the rules overmuch, but water hazards are so common that some mechanics seem desirable. Here is my house rule, which is derived in part from the AD&D Dungeoneer's Survival Guide and Wilderness Survival Guide.

Swimming and Drowning

• a swimmer’s movement rate is subject to multiple variables; these include any current, the swimmer’s direction relative to the current, and encumbrance
• an unencumbered or almost unencumbered swimmer—someone not in armor and with 5 pounds of equipment or less—has a movement rate of 50 feet/round
• swimming is possible at half that movement rate—25 feet/round—in leather armor so long as the swimmer carries no more than 20 pounds of equipment
• no swimming is possible in metal armor and an adventurer wearing it sinks to the bottom; with a saving throw, armor may be removed in one round and otherwise takes two rounds
• one can swim downward or upward—dive or surface—30 feet/round; if encumbered, he can dive triple or quadruple this rate and will surface half or a quarter this rate depending on how encumbered he is
• all underwater attacks are made with a -2 penalty to hit; ordinarily only thrusting weapons, like daggers or spears, do full damage in underwater combat
• an adventurer may hold his breath for a number of rounds equal to his constitution score divided by four; after that many rounds, an adventurer dies without air
• if a drowned adventurer is pulled from the water and an attempt to resuscitate him is made within a round or two, he may make a saving throw to avoid death by drowning