If you’re looking for interesting sciency tour I recommend http://vdome.co.za/
It’s a tour of the largest impact crater in the world. Graeme, the tour operator, is well informed on the geology and other science stuff. Possibly a skeptic event?
If you’re feeling sporty you can also do the optional river rafting and/or hike and/or mountain bike. Graeme points out interesting science features along the way.