Then, a little reassurance. Our 'Scout' went in (or Mitch the engineer as he is also known) to check all was good. And yes, he did return, memories were correct and it was a 3 metre dive down through the hole.
Some advise was given; don't come up too quick or you'll hit your head.
Finally I went down, using my hands to pull myself deeper and then along. Into the darkness I kept swimming thinking 'I better come up soon, my breath won't hole much longer.' Thankfully a friendly face popped down to show me I've made it (otherwise I would've kept swimming!). Perhaps I took the advise too far.
After the feeling of relief that I'd made it, it was then time to take in Mariner's cave. With a domed roof, the cave had stella mites, a resident sea snake (which someone nearly stood on), and light pouring from the underwater entrance. However, my favourite thing was the mist. As the tide came in, mist would fill the cave and then disappear when the water came out.
Leaving into the light was a hell of a lot easier than going into the darkness.
* picture by JB