Lakes
The core rules provide many of the basic mechanics for running encounters that take place on the water and keeping track of the party’s progress as they travel downriver. This section provides rules for exotic situations and combat on rafts, canoes, and other small craft. It does not provide rules for ship-to-ship com- bat, but it does provide you enough detail that you could resolve an artillery shot against a boat.
Rivers and Streams
The speed of a river’s flow is determined by a few factors. The downward slope of the land, the total volume of water flowing through, and the width and depth of the river’s channel all combine to determine its speed. Narrow, sloped, and shallow rivers move the fastest, as the tremendous volume of water must move through a small area. Larger, wider rivers move slower. The river speed table gives you some examples to determine how fast a body of water moves.
Swim
River Speed DC
Wide, flatlands river 10 ft. 10 Typical lowlands river 20 ft. 10 Narrow, jungle/forest river 30 ft. 10 Mountain river 40 ft. 15 Anything floating in a river moves downstream at the river’s listed flow speed. Consult the Swim skill description for check DCs. The ones listed in the example river table serve as a guide to how you should set a DC. In all but the most extreme conditions, a DC of 10 or 15 is sufficient. Reserve DC 20 checks for rough water, heavy storms, and rapids. A character who swims in a river automatically moves a distance downstream equal to the river’s flow. Enforce this movement at the end of a swim- ming character’s turn unless a PC uses up part of his movement to prevent this. For example, a character who can swim 15 ft. could spend 10
ft. of movement to prevent 10 ft. of down- stream movement. If a character spends move- ment in this manner, subtract the movement he spent from the total distance the river should carry him.
If a river’s movement carries a character into an object, he takes damage based on the nature of the object and his speed. Only barriers that could bring a PC to a complete stop can inflict damage, such as rocks, boats, or walls. Otherwise, a character moves through the object. If a PC would move through a crea- ture’s threatened area, he suffers attacks of opportunity if the creature gains them while in the water (see aquatic combat, below).
If in the DM’s judgment an object is solid enough to cause injury, a PC takes 1d4 points of damage for every 20 ft. of downstream movement, rounded down. Remember to account for any movement a character spent to reduce the distance the river dragged him. Also, use the total speed, not the distance the character moved, to determine damage. For example, a river that flows at a speed of 40 ft. would cause 2d4 points of damage if it swept a character into an obstacle whether his actual, physical movement for the round was less than the full 40 ft. If a PC spent 20 ft. of movement to reduce the downstream movement to 20 ft. for that round, he would take only 1d4 points of damage. When a character strikes an object, his movement ends for the round.
If a character wants to move upstream, he must spend enough movement to cancel out the effects of the river’s current. If he still has any movement left, he can then spend it as normal to move up river.
A character adjacent to an anchored or other- wise immobile object can remain in place by making a Strength check with a DC equal to the river’s speed divided by 4. If this check fails, the character is swept around the object and downriver. A PC can attempt this Strength check as a free action at any time during his downstream movement, but he can only make one such attempt per round.
Rapids
The fastest rapids send swimmers bobbing downstream at 40 to 90 feet per round. The Swim check DC to navigate these
difficult waters ranges from 15 for rapids with a speed of less than 60 ft. to 20 for anything faster. Use the rules given above for moving characters due to the river’s current and dam- age inflicted by colliding with solid objects. The primary danger offered by rapids is their great speed. While a character can swim with or against a river, the rapids move at such a fast rate that even skilled swimmers might be pulled beneath the water. Characters swept away by a river moving 40 feet per round or faster must make DC 20 Swim checks every round to avoid going under. Make this skill check at the start of a character’s action, before resolving anything else. If a character succeeds at this check, he can take his actions as normal. The rapids sweep him downstream at their movement rate as normal, and a PC could spend his movement to swim against the cur- rent.
If this check fails, a PC is swept beneath the surface and must hold his breath. See the Swim skill description for full details. The PC can take only limited actions for the round, as he struggles in the current. The buffeting water prevents all spellcasting and attacks are impos- sible. A PC can attempt to use a potion or other magical item. He can take one standard or move action per round and must make a DC 15 Swim check to complete the action. If he fails, he does not complete the action but suffers no further penalties. For example, a character who fails to drink a potion can attempt to use it again the following round. The potion is not swept downstream or ripped from his hands. A character cannot use this action to make anoth- er Swim check, as his initial failure represented his inability to stay above water.
A character being dragged downstream can receive help from others. A PC who is adjacent to him and has not been swept away or one who can reach him with a pole, branch, or similar aid gives him the opportunity to make a DC 10 Strength check as a standard action. If this check succeeds, the PC is no longer caught below water. If the person who aided him stands on solid ground, on a boat, or in a simi- lar position, the PC can move to safety.