What are substitutions in Water Polo?

Section 4: Players & Officials

In the water: 7 players per team (6 field players + 1 goalkeeper)
Roster: Maximum 13 players per team (11 field players + 2 goalkeepers)
A team must have at least 7 players to start a match
One designated team captain per side, identified by a captain's armband or cap marking

Unlimited substitutions permitted, but only from the re-entry area during a dead-ball situation or after a goal
Flying substitutions (during play) allowed only at the re-entry area; the departing player must fully leave the water before the substitute enters
Goalkeeper-to-goalkeeper substitution: the replacement goalkeeper must wear a red cap
Improper substitution (entering before the departing player exits) results in an exclusion foul

Center forward (hole set / 2-meter player): Positions directly in front of the opposing goal at the 2 m line; primary target for entry passes
Center back (hole-D): Defends the center forward; physical, pressing defense
Wings: Position at the sides of the attacking formation; drive and shoot from angles
Drivers (flats/points): Perimeter players who create motion offense through driving toward the goal
Goalkeeper: Special privileges within 5 m of own goal (may use two hands, punch the ball)

2 referees: One on each side of the pool; share equal authority; signal fouls with whistle and hand signals
2 goal judges: Positioned behind each goal; signal goals, corner throws, and goal throws
Timekeeper: Operates the game clock, records exclusion times
Secretary: Records goals scored, personal fouls, and exclusions for each player
Shot-clock operator: Manages the 30-second possession clock; resets on change of possession or reset events

In the water: 7 players per team (6 field players + 1 goalkeeper)
Roster: Maximum 13 players per team (11 field players + 2 goalkeepers)
A team must have at least 7 players to start a match
One designated team captain per side, identified by a captain's armband or cap marking

Unlimited substitutions permitted, but only from the re-entry area during a dead-ball situation or after a goal
Flying substitutions (during play) allowed only at the re-entry area; the departing player must fully leave the water before the substitute enters
Goalkeeper-to-goalkeeper substitution: the replacement goalkeeper must wear a red cap
Improper substitution (entering before the departing player exits) results in an exclusion foul

Center forward (hole set / 2-meter player): Positions directly in front of the opposing goal at the 2 m line; primary target for entry passes
Center back (hole-D): Defends the center forward; physical, pressing defense
Wings: Position at the sides of the attacking formation; drive and shoot from angles
Drivers (flats/points): Perimeter players who create motion offense through driving toward the goal
Goalkeeper: Special privileges within 5 m of own goal (may use two hands, punch the ball)

2 referees: One on each side of the pool; share equal authority; signal fouls with whistle and hand signals
2 goal judges: Positioned behind each goal; signal goals, corner throws, and goal throws
Timekeeper: Operates the game clock, records exclusion times
Secretary: Records goals scored, personal fouls, and exclusions for each player
Shot-clock operator: Manages the 30-second possession clock; resets on change of possession or reset events