Just looking at the pictures again brings back great memories ...
We found out about the place in a book called "Snorkel Maui and Lana'i", so it's not so hush-hush anymore.
However, the book has
lots of warnings about the rough trail there ... wear runners, bring water, have a hat, have sunglasses, no facilities at the other end, blah, blah, blah ... so we only saw dedicated snorkelers.
There are so many other snorkeling spots in Maui that are right off the beach (or those much hyped boat trips), that I'm sure this spot will be safe. Just too much effort for most folks.
My wife and I enjoyed it so much that we went back for a second day. The most impressive fish we saw was a 30 inch parrot fish (quite a beak on that one). When it rasped the rock to get at the algae we could hear the noise very clearly underwater.
Wouldn't want to get in its way !!