Hello random stranger! So today i was playing in mineplex, throwing people around and stuff (stacking) when i saw that mine place, with the skeletons named "miner". I saw the sign saying that there was no entry, so i figured that there would be a parkour down there soon or something. But than i saw this button through a hole in the cobblestone blocking the entrance to the cave. I pressed the button, and a piston pulled away a block allowing my passage. I went through and found myself in a cool secret underground area where you could see everything under spawn! You could even see the ender dragon that makes those random noises now and than! However if you want to go really low to really see everything, you'll find yourself in a 2 block high hole. If you dont want to drop down and die to get out of there, you should bring a friend along so he can use stacking to throw you out of the hole, so you can pick him up and get him out as well. 

You might be confused now, but you'll understand everything when your down there!
I posted a
photo to show you the view! Bye!
*UPDATE* I found out that this only works in a certain time of the day, and i got lucky showing up in the right time! So if it doesnt work at first, keep trying! If u get it to work, could you be kind and post in the comments what time did it work for you? Thanks! :)