Hezekiah's Secret Water Supply

I am conscious that this week's blogging is beginning to render me one of those bores who assumes the whole world wishes to see his holiday pics, complete with detailed and lengthy explanations. Heaven forbid. I wonder though if you might continue to indulge me. 
I spent a happy hour this afternoon wading through tunnels of water. It was thirty five centigrade outside, so the wet walls and submerged legs made the whole experience strangely pleasant. These are the tunnels of Hezekiah, king of Judah. He diverted the Gihon Spring in 2 Kings 20 and 2 Chronicles 32 so that Jerusalem might have a secure water source in times of siege, which the Assyrians would soon supply. With enemies outside cutting off the flow of food and drink, having your own water supply would be essential to life, hidden though it was to those outside. 
I'm mindful of Psalm 46 which reads There is a river, the streams whereof shall make glad the city of God, the holy place of the tabernacles of the most High. As believers, we have access to hidden strength and refreshment of which no enemy can ever know or estimate. 

Like a river glorious
  Is God's perfect peace,
Over all victorious
  In its bright increase.
Perfect, yet it floweth
  Fuller every day,
Perfect, yet it groweth
  Deeper all the way.

Stayed upon Jehovah,
  Hearts are fully blest,
Finding as He promised,
  Perfect peace and rest.

Hidden in the hollow
  Of His pierced hand,
Never foe can follow,
  Never traitor stand.
Not a surge of worry,
  Not a shade of care,
Not a blast of hurry
  Moves the spirit there.

Every joy or trial
  Falleth from above,
Traced upon our dial
  By the Sun of Love.
We may trust Him fully
  All for us to do,
They who trust Him wholly
  Find Him wholly true. 

Frances Havergal (1876)