This is a very simple trap-kind creation of mine after messing up with my TNT elevator. I believe no one wants to build this in legit survival, so I post it as a schematic here. It looks pretty awesome so that makes me share it.
This Nuke is purely made of dispensers and a redstone clock mechanism, each dispenser contains 20 TNTs, which will be all dispensed after the 1st one explodes. It creats huge explosion and it destroys almost everything!!
The world which I did my test in was one of my survivals'. Before you rate it, please try it 1st, it's simple but awesome. Destroy your own world and see what you get :D!
Note: In survival or adventure mode, you may simply modify it by putting a boat on a pressure plate instead of the lever, then detonate the bomb with an arrow shot from afar. Don't forget to take out all TNTs 1st, or you might just be completely obliterated. Good luck!