Tutorials/Igniting TNT underwater

Making TNT explode underwater seems impossible, especially if you're not using the Education Edition. However, with this special glitch, you can create explosions even though you're in water!

Materials needed

 * 1 sand, gravel, or concrete powder
 * TNT
 * a flint and steel or fire charge
 * any kind of building block, but not too expensive(recommended, to   reduce the fail chance)

Steps

 * 1) Find any body of water. It could be a lake, river, or in the middle of an ocean.
 * 2) Place the TNT block, with a block of sand or gravel on top.
 * 3) Ignite the TNT with your flint and steel then step back and watch the magic happen. (Note that the TNT would move slightly when it's ignited, hence a few blocks are needed to prevent it from happening.)

Video tutorials
OMGCraft's design:

Creator's (Jun631) design: