Quite a few topics, actually... I recently gave a presentation on Guédelon castle - a modern day recreation of a medieval castle using only medieval tools and methods in France - and the 5 minute preparation I had for it was used only on looking up and putting together some photos to put on. If it's a topic I'm already passionate about I probably have spent a lot of time researching it already. And there are a lot of different topics I'm quite passionate about... history/prehistory (basically the past up until the 1700s), lots of different animals, physics, math, languages in general and the few I speak in particular, ships and sailing, some political things like taxes and health insurance, sexuality and gender, ... I probably forgot more than half in this list and I already condensed down a lot of things into groups... 😅