In no particular order.
1. Just who was Jack the Ripper? Could it have been more that one person? Copycat killers? Inter-dimensional time travelling being?
2. What happened to HMS Terror & HMS Erebus? Is there a chance that under the ice we will discover very well preserved 19th century ships, complete with logs and personal diaries that will finally explain the whole sorry story? Was it more than just lead poisoning, scurvy, botulism, cannibalism and extreme conditions that eventually killed everyone off? Did anyone actually survive but traumatised by their experiences or actions spend the rest of their life in silence?
3. What sort of strange creatures might be undiscovered in the sea? I don’t believe in Nessie (as much as I’d like to) but I think it is very possible that there are similar sorts of creatures just waiting to be discovered. I possibly think that there are strange land creatures that have yet to be discovered but the more I think about it the more unlikely it seems.
4. Why do TV executives think it’s a good idea to end shows that aren’t doing so well on cliffhangers that they are most likely never going to come back and resolve? ‘Surface’ I’m talking to you here.
5. What happened to the lighthouse keepers of Flannan Isle and what happened to the Mary Celeste? Why do so many fictional things continue to be associated with it? In both cases there were no half eaten meals left on the table (that comes from a story by Sir Arthur Conan Doyle called ‘J. Habakuk Jephson’s Statement’) and they certainly weren’t turned into three strange birds! (That comes from a poem by Wilfred Wilson Gibson)