How does a penalty throw work?

• Any player of the awarded team takes it from any point on the opponents' 5 metre line.
• All players leave the 6 metre area and stay at least 3 metres from the thrower. One defender on each side of the thrower on the 6 metre line has first right to take position. The defending goalkeeper stands between the posts with no part of the body beyond the goal line at water level.
• You may give one warning to a player or goalkeeper to take the correct position. If they still do not, that player or goalkeeper is excluded.
• Signal the throw by whistle while lowering the arm from vertical to horizontal.
• The thrower must have possession and throw directly at the goal in one uninterrupted movement. The ball may be lifted from the water or held in the raised hand and taken backwards in preparation, as long as the movement is not interrupted before it leaves the hand.
• If the ball rebounds from the post, crossbar or goalkeeper it stays in play, and no other player needs to touch it before a goal can be scored.
• In the last minute of the game, the coach of a team awarded a penalty throw may instead choose to keep possession and take a free throw, with a clear signal and no delay.

Source: World Aquatics Competition Regulations Part Six, Article 15.