The 100m freehanging abseil will astound you, but on this option that's only the beginning. Spend the rest of the day walking, wading and swimming through the cavernous passages of this famous underground system. Yes you need to be moderately fit (e.g. go bush walking for a day), but the trip is intended for complete novices - all you need is a swimsuit & a smile! See Fossil giant oysters and whalebones; giant flowstone (looks like icing sugar running down the walls). Lots of fun & optional challenges - water jumps; climbs and spiders. Includes an absolutely fantastic glowworm display. Includes lunch & a BBQ dinner as well as all equipment (helmets; lights; wetsuits; ropes; harnesses & boots). This will be the highlight of your world trip.