Back in the day (1860-ish) when Mapua was called “Seaton Township”, the port area was known as the Western Entrance (to the Waimea Inlet).
The Eastern Entrance (or Blind Channel) doesn’t lend itself to maritime navigability one bit – you have to squeeze through between Best and Bell (hold your nose – it’s the location of Nelson’s sewage oxidation ponds) islands and then go either south of Rough or north between Rough and Rabbit.
Either way, you’ll have to duck your head to get under the causeway.
Best performed in a kayak at high tide.
Best to avoid it at all costs, actually.
Just watch out for the bar at the Western Entrance, though.
Dennis Crawford got standed out there once – claimed his boat was tired and wanted to lie down until the next high tide….