The Breakwater is one mile long. It is made up of huge blocks of granite all the way out to the lighthouse at the end. Although the stones are not level and you need to watch your step a bit, this is a beautiful and fun walk to the lighthouse.
I have walked this several times over my lifetime. The first was as a child with a friend. I remember we found starfish at the water's edge. I have returned many times since. Even if you don't want to walk the whole way, the walk down to the Breakwater from the parking lot has benches for watching the harbor.