It's from a church/community in Spain.  They have a prayer area in their facility with hanging blue bottles for private prayers.  I have no idea how they get the prayers out, but it's a wonderful look.

You can find the following on their website.  

MESSAGE IN A BOTTLE
Prayers for God alone to hear
“Just a castaway, an island lost at sea 
Another lonely day, with no one here but me 
More loneliness than any man could bear 
Rescue me before I fall into despair”
Sting 



Write a prayer or a letter to God.
Tell Him your secrets, your longings, your hopes, your dreams, your fears – anything you like really.
Roll it up and put it in a bottle for no one else to read

“You keep track of all my sorrows.
You have collected all my tears in your bottle
You have recorded each one in your book’
Psalm 56 : 8