Boulder Bay is a secluded bay on the coast at Sumner, Christchurch, rated 4.8 from 4 Google reviews. Reviewers describe a coastal walk from Taylor's Mistake along a wide track that suits walking or running, and a quiet bay that is a good place to stop before going on towards Godley Head. One mentions a swim at Taylor's Mistake on the way back as a good way to cool off in summer.
A coastal walk to a bay is judged on the track's surface, how exposed it is to wind and how far the route runs. Coastal tracks can be windy and rough in places, so check conditions and tide times before setting out. Sea water is often cold even in summer, so bring a dry layer for afterwards. Many visitors walk out and return the same way, which makes the day easier to plan.
For a coastal walk and a quiet bay near Sumner, Boulder Bay is worth the trip.