I did the "lazy" thing and just parked at Lake Surprise, part of Mt Eccles National Park, which is easy as long as you have your own car. It was way back in 2018 so maybe things have changed now - for one it's actually inscribed as a UNESCO property now and the path around the lake is actually clear. Back in the days I met with the caretaker (more of a hippie that was doing this on the side) and he was a bit concerned that logs had fallen onto the path - and he made sure I would drive safely to avoid hitting 'roos - mkay.  The path around the lake is usually quite easy and doesn't take too long. You can see plenty of birds this way too. From this area you can hike more inwards for the lava tunnel and "natural" bridge. Overall you are ok with half a day here and that's what I did on a drive-by. Naturally, I missed two other areas (which perhaps weren't cleared marked back in the days) but I wouldn't go back for it. I don't think this is a huge phenomenon to visit. I think what was nicer is that the entire area was empty and one is alone for a bit.