Underwater Torch

Underwater torches are non-solid blocks that emit light underwater.

Breaking
Unlike normal torches, it will not break if water occupies its space. This makes it the only means except jack o'lanterns and some other blocks to provide light under water.

Like normal torches, an underwater torch breaks instantly and drops itself when broken using anything. The tool does not take any damage when breaking the underwater torch.

Underwater torches are also broken if pushed by a piston.

Crafting

 * The torch can be crafted with coal or charcoal. The player can also use a torch from the creative menu.

Usage
Underwater torches can be placed on the top or the sides of most solid blocks, although some require (see placement for exceptions). Being non-solid, underwater torches have no collision box.

Gravity-affected blocks like sand and gravel does not fall if the block below them has an underwater torch on it, and break if they fall onto an underwater torch.

Placement
In general, underwater torches can be placed only on solid, opaque, and full blocks; exceptions are listed below.

Light
Underwater torches give off a light level of 14. Underwater torches also melt snow layers and ice within 2 blocks (taxicab distance).

Trivia

 * Magnesium actually does not burn underwater on its own. However, magnesium and iron oxide make up a mixture called thermite that burns hot and bright anywhere, in or out of water. This is because the magnesium can take oxygen from the rust.