[Torchwatch]

The function of a ladies swim or shower cap (with plastic flowers) is to keep your hair dry and free of chlorine.

The function of a rubber or silicone racing swimmer's swim cap is to reduce drag from your hair in the water, different colours and prints denote different competing clubs and teaching groups may issue and award different coloured swim hats to different ability classes in the manner of martial arts belts.

Water polo caps are used in any contact sport played in and under water to protect the eardrums from sudden compression and decompression which might rupture the eardrum. Again teams select their own colours text and logos since players have only their swim briefs and caps denote which team they are on.

Beach lifeguards traditionally wear cotton red and yellow swim caps with under the chin ties. As lifeguards work as a team they need to be able to identify each other from a distance especially in the water and monitor one another's progress. At lifeguard competitions lifeguards wear their club colours (most lifeguard clubs are attached to swimming clubs) and adopt a matching swim cap.

As with so many things your choice of swim cap depends on what you are doing, without knowing that it's not possible to know which is best.