Right across the street from the ferry you will find Harbor Grill (inside the Harborside Inn). One of the reviews from last summer was right on point so we will share it here:
“Fantastic!! Great view, great food, and great service! Best meal we had on our short visit to Block Island. Came for dinner. Had the caprese, wings, and spinach & artichoke dip for appetizers (though the dip was served with wonton chips which was odd to us). We had seafood Louie’s, ahi tuna special, NY strip special, and burger for dinner. All were incredible! Highly recommended!!”