Glowstick

The glowstick is a form of usable light in Terraria. Although glowsticks do not cast as much light as a torch, it has other unique characteristics that make it a viable utility even in the late game. In recent patches, torches no longer casted light when held in water. So, in order to produce light underwater without the aid of an Orb of Light or a Shine Potion, the glowstick was introduced.

When right-clicking while highlighting the glowstick, the player will throw the glowstick and it will roll, similar to dynamite, emitting a low level of light. Unlike torches, when the glowstick is thrown using the right-click, it cannot be picked back up, which allows for quick, on-the-fly light sources. It also should be noted, however, unlike the torch, when a player presses the throw item button [Default: Q] the entire stack is dropped, but can be picked back up.

Glowsticks are dropped by Jellyfish.