Clearing a mountain?

I finally built a floating island for my house, I used so much cobble smelting and it’s located above a large mountain for now.

For it to be finally seen in all its glory, I just want to get rid of the whole mountain. Is it quicker to break it by hand with efficiency III or to farm creepers for TNT?

Anything else I should consider before undertaking this? It’s not like I wanna blow up my island and everything else with it.

Also if TNT is the best way, how should I go about farming creepers and how much would I need it?