The Basics

• A team consists of five people.
• Games are played in two halves of between six and ten minutes long.
• At the start of play, each team line up with the back of their boats on their goal line. On the whistle the players can move but only one can go for the ball which is thrown into the middle of the pool.
• The ball can only be held for five seconds before it is passed (to yourself or another player).
• A player must not do anything that endangers another player or themselves.
• You are not allowed to touch another player, their boat or equipment with your paddle or body.
• The ball can be played (or flicked) with the paddles.
• Paddles are not allowed to be placed within arms reach of a player in possession of the ball or used to propel off another boat or the side. If the paddle is used to reach across a boat there must be no contact.
• If somebody swims, all their equipment must be taken off the pitch then a substitution can only take place at the next break in play unless they and all their equipment is taken behind their goal line or if they want to re-enter the game it must be done from their own goal line.
• Play stops when the referee blows the whistle. The referee will indicate why play has stopped using the following signals.
• If the referee calls a foul, they will indicate which team now has possession. One arm will indicate the direction of play (DOP) normally with a finger pointing at the opposition goal indicating a free shot (direct) for a foul or with an open palm stretching along the side line indicating a free throw (indirect) for a ball out of play. The other arm shows the infringement.
• After a whistle is blown for a foul etc the restart must be made by presenting the ball at arms length above the head before playing it.
  

Common signals

Free throws (indirect):

Goal Throw - One arm shows DOP, other arm outstretched parallel with goal line.
Side line - One arm points downwards indicating where the ball went out of play, other shows DOP. To take the sideline, the boat must be parallel and against the side line.
Corner - Same signal as side line but can be taken from either corner. To take a corner the player must line their boat up against the sideline as close to the corner as possible.
Goal - Arms extended palms together pointing to centre of pitch
After a goal is scored, each team returns to their own half and a player from the team who conceded the goal presents the ball in the centre, waits for a whistle then play is restarted.
Half/Full time - Signalled by a long blast on the whistle, arms crossed in front of chest.

Free shot (direct):
 
Paddle foul - One hand showing DOP, the other making a chopping motion on upper arm.  You must not make contact with another player or their boat with your paddles.
Illegal tackle (Kayak or hand) - One arm DOP, other hand on hip.  Some boat to boat contact is allowed if you are tackling the player in possession (see later) of the ball but the end of your boat should never enter the cockpit area or touch another player’s body. Ramming is also not allowed. Coming in at speed, broad-siding another boat, is a foul.   If a foul is called the ball may be played from where the foul is or where the ball was at the time which ever gives the most advantage.  Once in position to play the ball you only have 5 seconds to throw it a minimum distance of one metre. The referee will indicate where to play the foul from.

Legal Moves
 
Goalkeeping:  The goalkeeper defends the goal by holding the paddles upright and blocking the ball with their blade. When they have their paddles raised under the goal with the opposition in possession, the opposition are not allowed to push the goalie out of position. There must be no boat to boat contact between opposition and goalie. Also the opposition must not push a defender onto the goalie. However players must actively try to avoid being pushed onto the goalie for a foul to have occurred (illegal kayak tackle). Players may not stop a goalie trying to take up position under the goal.
Possession:  A player is in possession if they have the ball in their hand or the ball is in the water and within arms reach of that player or they are manoeuvring the ball with their paddle. If a player is in possession of the ball they may be tackled for control of the ball.
Hand Tackling:  The player in possession of the ball can be hand tackled by the use of a single open hand pushing the opponent’s side, upper arm or back. Don’t push the player on to the side of the pool or onto another boat as this is illegal. Alternatively the ball can be knocked out of somebody's hands with your hand so long as only the ball, not the player, is touched.
Kayak Tackling:  The player in possession of the ball (or attempting to gain possession within 3 metres of the ball) can also be kayak tackled. You do this to try and steal the ball when it is in the water or to force a bad pass. You are not allowed to tackle the boat at an angle of between 80 and 100o. Avoid the body and the spray deck area of the kayak.
Illegal Jostle (Illegal tackle signal):  Within the six metre area players are allowed to jostle for position. However if they are trying to maintain position they are not allowed to be pushed out of that position by more than half a metre by an opponent.
Illegal holding/screen (Obstruction):  One hand DOP, other hand holding up a clenched fist
Holding:  Players are not allowed to lean on an opposition boat; or impede or hold on to a player or his equipment.
Illegal Screen:  If a player has not got the ball they have the right to paddle unimpeded towards the goal or the ball (unless they are within 3 metres of the ball) from anywhere in the pool outside the six metre zone. This means players may not move their boats to deliberately obstruct somebody's path or force them into the side. Although once set up in a position, they are allowed a static screen (without active paddle strokes).

Advanced signals
 
Advantage:  One hand shows DOP, the other waves on at hip level.  If the referee decides that calling for a foul would unfairly disadvantage the team in possession, advantage may be played by the referee shouting play on and signalling by waving a hand forward at hip level.  If a whistle has been blown, advantage cannot then be called.
Time Out:  Open hands forming a T at chest height.  Called to stop the clock if there is an unreasonable delay (equipment problem, injury etc) or if a referee’s ball or penalty shot is called. Play restarts on a whistle.
Referee’s Ball: Both hands show thumbs up at chest height.  If the referee blows their whistle when neither team was at fault, or in sole possession, a referee's ball is called. A player from each team lines up, tip of the kayak touching the sideline 1 metre apart, paddles by their side and hands on their spray deck and the referee throws the ball between them. The ball is not in play until it touches the water.

If anyone wants to see what the hand signals actually look like the are shown here. http://www.canoepolo.org.uk/rules/signals

Sanctions
 
Free Throw: The hand showing DOP is open, palm parallel to the side line.  Awarded for all balls out of play (corner, side line, goal throw), start infringements, centre restarts and failing to present the ball.  This is indirect so the ball must be dribbled, passed or touched by the opposition before a shot on goal can occur.
Free Shot: Signalled by a pointed finger at the opposition goal.  Awarded for almost any foul. The ball can be played anywhere, including at goal.
Penalty Shot: Both hands pointing a finger at goal followed by time out. If a player is fouled in the act of shooting in the 6 metre area or a foul is deemed particularly nasty a penalty shot may be awarded.  All players retreat to the halfway line and one player sits on the 6 metre line and has a free shot at an open goal.  If the ball fails to reach the goal or rebounds off the frame, somebody else must touch the ball before the initial shooter can.
Cards: Shown after a time out signal.
    Green card - warning for unsporting conduct.
    Yellow card - sent off for two minutes (after two greens or something nasty).
    Red card - sent off for the rest of the game (after two yellows or something very nasty)

Click here for details of signals!

Thanks to Dominic and Len for this page!