Hokitika is the site of dozens of shipwrecks over the years (wouldn't you know it?). The mouth of the river at the Tasman Sea is sometimes barely navigable.
In addition to all the driftwood, the shore gathers smooth rocks, such as the pinky-white ovals I mentioned earlier. Vic and I are sure we saw jade among the rocks. Jade is supposed to be ejected from seams in the mountains.