I spent a day at the London Natural History Museum and managed a few quick drawings here and there. Not exactly sketching in nature, but essential to learn about the details and the anatomy of the animals. I learn a little from every single sketch I make, and it makes me that tiny bit faster when I draw animals in action.
If you love science illustration as much as I do, you can now enjoy this great mooc for free: https://www.edx.org/course/drawing-nature-science-culture-natural-newcastlex-nhi101x
