Underwater Torch

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

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

From block loot
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.

From crafting

 * The torch must be crafted with charcoal

Info
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.

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 rust 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.