One brilliant source of inspiration for enquiry lessons has to be BBC documentaries, and in particular Simon Reeve.
"What is Simon doing in the desert?", based on a clip from an episode (below) from his Tropic of Cancer series. Students learnt about the Namib desert and how sand dunes are formed before discovering that Simon was sand boarding; the newest tourist craze in Namibia involving hurtling down a huge dune on a piece of what can only be described as MDF.
I have been watching his Australia series (still available on BBC iPlayer) and it has been inspiring me with new ideas for lessons. During the first episode you could create a lesson on biodiversity in the outback of Australia - feral camels who have started to destroy the local ecosystem have been rounded up to manage and control their numbers. "Why has Ian been rounding up camels?"
In the first episode, there was also a story about millionaires who made their money from tuna fishing in Port Lincoln in South Australia - "Why are there so many millionaires in Port Lincoln?" - could be used to explore the issue of overfishing and whether certain species of fish should be protected.
Or you could even use it to teach about economic migrants. One bin man left his life in Hull to teach people to drive trucks in Australia where he can earn enough money to buy a speedboat. Many UK migrants are moving to Perth to have a better lifestyle with a larger income. "Why did a bin man leave Hull to move to Australia?"
I hope that the next two episodes give me just as many ideas for future enquiry lessons!