Yes, you'll find most hotel room reservations are fully refundable as long as you cancel prior to the accommodation's cancellation deadline, which often is within 24-48 hours of the scheduled arrival. If you booked a non-refundable reservation, you might be able to still cancel and get a refund within a 24-hour period of booking. Add your dates and click on "Search", then use the filter option "fully refundable" to get the top deals on offer near Arnhem Marine Park.
