Fifteen of the caches are at the coordinates given for them. You need to record the number inside the lid or on the outside of each cache to find the coordinates to a 16th cache (GC6NN4W) that contains a special geocoin for the FTF, featuring something else that Island Bay is famous for.
The coordinates for the 16th cache are South ABo CD.EFG East HIJo KL.MNO, where A is the number inside the lid of River Roads #1 – Dee Street, B is the number inside the lid of River Roads #2 – Tamar Street and so on up to O, which is inside the lid of River Roads #15 – Severn Street.
Avon Street
Avon Street is named after the River Avon in the UK, which adjoins the counties of Leicestershire, Northamptonshire, Warwickshire, Worcestershire and Gloucestershire in the Midlands of England. Also known as the Warwickshire Avon or Shakespeare’s Avon, it has been divided since 1719 into the Lower Avon, below Evesham, and the Upper Avon, from Evesham to above Stratford-upon-Avon.
The source of the Avon is from a spring near the village of Naseby in Northamptonshire. For the first few miles of its length between Welford and the Dow Bridge on Watling Street, it forms the border between Northamptonshire and Leicestershire. On this section, it has been dammed to create Stanford Reservoir. It then flows in a generally west-southwesterly direction, not far north of the Cotswold Edge and through the Vale of Evesham, passing through the towns and villages of Welford, Rugby, Wolston (bordering Leamington Spa), Warwick, Stratford-upon-Avon, Welford-on-Avon, Bidford-on-Avon, Evesham and Pershore, before it joins the River Severn at Tewkesbury.
The river has a total length of 85 miles or 137 km and a catchment size of 1,032 square miles (2,670 km2). The Avon's tributaries include the Rivers Leam, Stour, Sowe, Dene, Arrow, Swift, Isbourne and Swilgate, as well as many minor streams and brooks.

The cache
This is a straightforward park ‘n’ grab, but is in a residential area, so please respect the residents’ privacy and be discreet. It’s on public land, so there’s no need to enter any private property. Bring your own pen or pencil.
You’ll be near Erskine College, a collection of historic buildings and landscapes, including the Chapel of the Sacred Heart and Main Block Convent. Built from 1905-6 by the Society of the Sacred Heart (Sacré Coeur), the buildings served as a Catholic girls' boarding school (Convent of the Sacred Heart at Island Bay) until its closure in 1985. The name was changed to Erskine College in the late 1960s to avoid confusion with Sacred Heart College, Lower Hutt. The buildings and grounds are now classified as a Category 1 ("places of special or outstanding historical or cultural heritage significance or value") historic place by the New Zealand Historic Places Trust and it has most recently been occupied by the Learning Connexion, an art school.
You are looking for a black Bison tube. The number you need is on the outside. Please replace it exactly as you found it and do please log a DNF if you can’t find it. There’s no shame in a DNF! This is particularly important, as this is a series of caches in which all need to be active for finders to locate the final cache.