A pool noodle is a cylindrical piece of polyethylene

Polyethylene

Polyethylene or polythene is the most widely used plastic, with an annual production of approximately 80 million metric tons...

 foam, sometimes hollow. Pool noodles are used by people of all ages while swimming. They are useful when learning to swim, for floating, for rescue reaching, in various forms of water play, and for aquatic exercise. Pool noodles are particularly useful to support amateur snorkelers.

A pool noodle connector is a piece of pipe made out of foam, slightly larger than a pool noodle so that it can connect two pool noodles by encasing the end of each. This allows larger structures to be built from pool noodles. There exist at least two-, four- and six-hole connectors.

A "Noodleskin" is a custom cover that is placed over a foam pool noodle which allows 2 pool noodles to be made into a floating seat.

Other uses

Medieval warfare LARPs often make extensive use of pool noodle with such cores for foam weapons. It is generally the least expensive form of construction available and very easy to make into a safe weapon, however pool noodle foam is more prone to break down with extended use than other types of foam.

Modern Martial artists occasionally use pool noodles as Tameshigiri

Tameshigiri

Tameshigiri is the Japanese art of target test cutting. The kanji literally mean "test cut"...

 (test cutting) targets, in lieu of more expensive targets like meat or tatami omote mats.

FIRST Robotics Competition

FIRST Robotics Competition

The FIRST Robotics Competition is an international high school robotics competition organized by FIRST. Each year, teams of high school students compete to build robots weighing up to , not including battery and bumpers, that can complete a task, which changes every year...

robots use the foam from pool noodles as a bumper to protect the robots from damage during collisions.