Cape Cod Mystery Shrub

I was down on Cape Cod a few days ago and the old Cape standard, Hydrangeas, was making it's annual appearance. Profusions of blue blooms were enjoying the salty air. Just gorgeous.

This year I noticed another shrub that was blooming blue'ish and didn't recognize. Perhaps another type of Hydrangea? Here's a pic:

I must do my homework on this one......