How do I open the door in the tunnel?

Hint 1 of 11:

Even with your superhuman strength, you just don't possess the power to break
open this door.

Hint 2 of 11:

A huge explosion might take it out, though.

Hint 3 of 11:

If you've been to the marine dropship, you should remember seeing a missile
lying on the ground.

Hint 4 of 11:

Guess what makes a missile go *boom*.

Hint 5 of 11:

Explosives, of course!  Head back to the island, and open the missile.

Hint 6 of 11:

As soon as the game lets you, pick up the bomb and run!

Hint 7 of 11:

Head back to the door, making your way across the blocks as quick as
possible.  Whenever the timer pops up, just press ESC quickly.

Hint 8 of 11:

Once you make it to the door, press "I" to put away the cube, and then press
Enter to drop the bomb.