Heading back from the post-swim BBQ (more on that later), we detoured a bit to visit Tank Farm. The picture above doesn’t quite do justice to how this looks in context… it’s a pretty dramatic half-mile hole in the ground! We appreciate the sense of humor in the cautionary sign, probably not official Auckland Council issue.
This is one of the oldest volcanoes in Auckland. It erupted about 200,000 years ago. For most of that time, it was a freshwater lake right next to the sea, but at some point the crater wall collapsed, allowing tidal waters to enter, along with a whole lotta silt.
It got the name Tank Farm because the US Navy started to build fuel tanks here in WWII for its planned assault on the Japanese. But the course of the war changed before the tanks got past the foundation stage, and now all you can see are faint round outlines along one edge of the crater.