We were all up next morning by 7.45am. A thick fog covered the campsite, but it eventually lifted to reveal a clear warm sunny day. Today's walk would see us crossing the nearby Shoalhaven River and ascending to The Big Hole and then continuing on to Marble Arch. This walk is one of the most popular walks in the Deua National Park. At 9.50am we set off along the foot track to reach the river, less than 200 metres from our campsite. I had worn my river sandals for the short first section and carried my bushwalking boots and socks. The river was swollen after a mixture of snow thaw and recent heavy rain. I'd not seen the river this high before and the last time I'd been here we had crossed on stepping stones without getting our feet wet.

The next 20 minutes was spent crossing the icy fast flowing water which still barely got above knee level, but still numbed our feet. On the other bank we needed to dry our feet and put on socks and boots. Instead of carrying our sandals and water shoes on the walk we hid them behind some bushes for the return crossing. We now headed eastwards slowly ascending a large hill as it first passed through light forest, then steeply ascended through low heathland that gave great views to the west of nearby Bunhybee Hill and to the Great dividing Range to the west. Along the way we had all been looking for suitable trekking poles in the form of fallen timber as we had all forgotten to bring our hi-tech walking poles with us. We would cast off poles as better ones presented themselves. By the end of the walk we all had impressive looking wooden staffs.

Not long after the ascent levelled out we found ourselves at Big Hole, not 50 minutes after we had commenced our walk. The Big Hole is a huge sinkhole created when the roof of an underground limestone cave collapsed. From the safety of our viewing platform we can look down the 100 metres to the base of the hole which is level with the Shoalhaven River. We can see the sedimentary layers in the walls of the hole and interpretive signs inform us we may see a lyrebird if we are lucky enough. We weren't. I found it interesting to look down on ferns growing on the rubble pile at the bottom which resembled a nice green ground cover before being informed by the information board that those 'Tree Ferns' were 2 metres tall.

We continued on, descending now through the forest, still following a well defined foot track. Craig continued in front heading straight ahead where a post had been placed and a nearby tree had a pink ribbon tied, making it obvious you continue straight ahead, but a close look at the top of the post revealed an arrow pointing to the track to the left, the ribbon had been placed in the wrong position. Craig was recalled and we continued on with our descent until we reached a dirt road. This is the Bettowynd Fire Trail. We cross this to the track on the other side and continue eastwards through what now appears to be a mixture of forest and old farmland.

On the trail we come across an old termite mound which had a large hole at its base which appears to be dug by a small wombat. It's quite obvious that an echidna has created this and over time has wiped out the inhabitants. This mound is nothing more now than an interesting stop on the trail. The track continues through interesting forest until we come to a large grassy laneway with old rusted steel parts on an embankment. It is possible this is an old irrigation channel that has now dried up. The grassy area is still quite swampy but we were able to cross the wettest spots with the help of rotting timber posts sunk for walkers to utilise.

We follow the trail through more forested countryside where fallen trees have been chainsawed to allow walkers to remain on the track. There are plenty of kangaroos and wallabies to be seen, all of them bounding off at our approach. We eventually come to a distinct right hand bend in the track with a signpost directing us to Marble Arch. The track leads us to an information board telling us about the arch before the track commences its descent to the creek far below.

The track now descends quite steeply down the spur via steps that have become covered in leaf litter. The descent is around 100 metres and at one stage a break in the trees reveals a grand view of the mountains to the south-east. After negotiating under a large fallen tree the track ends at a small level clearing that has obviously been used as a small campsite in the past. It is 12.25pm as I lead both Craig and Leith down a small gully to our right and after brushing past some overgrown vegetation, find ourselves in a little slot canyon, a dry creek bed covered in stones and rock fragments. As we turn the bend we enter a large opening between two rock slabs below a boulder trapped above us.

The creek in flood has carved through this subterranean cavern, just a small field of limestone and marble in an otherwise landscape of sedimentary rock. The water has carved out levels and niches in the rock which contain what look like small stalactites. The light coming in from the openings above is quite bright and reveals mosses and ferns on the shelves above us. Photography was hard but I did manage to get a couple of shots that are worth keeping. We spent a fair amount of time looking around before returning to the small clearing where we sat on a fallen log and had lunch.

At 1.30pm we put our rucksacks back on and set off on the steep ascent back to the top. I stated to both Craig and Leith that this would be no race, everyone was free to take their own pace, take their time and the only stipulation was that everyone would wait at the top and allow the last person arriving to take a breather. The ascent was slow and strenuous. I took all the breaks I required and soon reached the top and waited for Craig and Leith to catch up. They werentt too far behind me.

After a rest we set off for the campsite, this time taking in all the sounds and sights from the bush around us as we slowly made our way back. We attempted to pick out what appeared to be old farmland in the forest. As we passed by the old termite mound Craig noticed an echidna not far from the track. We stood and watched it for a few minutes knowing if we approached it to take a photo it would bury itself in the soil.

We crossed Bettowynd Fire Trail and started the ascent back to Big Hole where we had another break. Leith considered this ascent harder than the one out of the Marble Arch gully, but obviously it was the smaller ascent at the end of the day making it feel harder. We descended the trail back to the river, retrieved our crossing footwear and crossed over. Being the first across I took the opportunity to take some footage of Leith and Craig attempting their crossing. We arrived back at the campsite at 4.40pm. We had enjoyed a 12km return journey and completed what had been for me, a must do since I originally did the walk to Big Hole in 2009.