This is very close to one of my ealy geocache finds.
Unfortunately the original was recently archived, see GC5EC5H
Here you get a great view of the SH1 Wairau River road and rail bridges, and see where the Wairau river splits off into the Diversion, providing a direct route to the ocean and reducing flood risk.
Cache is a 1l plastic screw top container, with a log and pen.