It's traditional to tie a thread of blue into our tzitzit (the fringes on our prayer shawls).
Some say this is to remind us of when our ancestors "went up" to God and saw a sapphire floor that was "like" a floor beneath a throne that was "like" a throne. (I'm putting those words in quotes because -- as parashat Mishpatim makes clear -- an encounter with God is necessarily beyond all language.)
Others say that the blue thread in our tzitzit is "just" the blue of sky -- no need for mystical visions of sapphire, the blue threads simply remind us of the heavens. Still others see the blue thread as the blue of the sea. Maybe it's the blue of sea reflecting sky reflecting sea in endless conversation.
This morning I davened shacharit (morning prayers) from my little mirpesset (balcony) overlooking the water. I'm profoundly blessed to be spending this week in a place where I can see the sea, and the sky, in all of their ever-changing splendor.
One of the standard morning blessings praises God Who spreads the earth over the waters. Today I inverted it, blessing the One Who covers so much of this planet with the wonders of the sea.
Shabbat shalom to all who celebrate.