UNDERGROUND HOTEL ETA inforamtion essentail Private tours of motel and working mine available. The BEST place in Australia to buy Australian Opals. Au Star Rating 3. Front Desk Hours: 7:30-9:00pm. If arriving outside of these hours, please contact hotel in advance for arrangements. Children charged as adults at this hotel. Exact ETA required for ALL guests arriving via the GHAN, bus or plane.